I descaled and the machine keeps coming up with descaling on the display window

17.3 Descale
Over time, the continuous heating up of the water used to make the coffee leads to lime scale building up in
the inner circuits of the appliance.
When the message:
DESCALE
flashes on the display, you should perform the descale cycle.
Proceed as follows:
• make sure the appliance is ready.
• press the P button (the light over the button comes on) then press the button repeatedly until the
appliance displays:
DESCALE No
• Press the button (corresponding to the SET symbol flashing on the display) and the appliance will
display:
DESCALE YES
• Press the OK button to start the descale programme.
• Empty the tank and pour in the contents of one bottle (125 ml) of DURGOL descaler plus one litre of
water.
For subsequent descaling, use descaler of the same type and brand as supplied (available from technical
service centres authorised by the manufacturer).
• attach the water spout to the nozzle;
• place a container with a minimum capacity of 1.5 litres under the hot water spout (Fig. 3);
34 C o l l e c t i o n
• press the OK button.Descaler runs off from the hot water spout into the container below.
The appliance displays:
APPLIANCE IN DESCALE
• the descale programme automatically performs a series of run offs and pauses to remove lime scale
deposits from inside the coffee maker.
• After about 30 minutes, the appliance displays:
RINSING FILL TANK
The appliance must now be rinsed through to eliminate residues of descaling solution from inside the appliance.
Proceed as follows:
• empty the water tank, rinse and fill with clean water.
• Reposition the tank.
• Empty the full container and then put it back under the hot water spout.
• Press the OK button. Hot water is run off from the spout into the container below and the appliance displays:
RINSING
• When the water tank is empty, the appliance displays the message:
RINSING COMPLETE PRESS OK
• Press the OK button and refill the water tank with clean water.
• The descale programme is now terminated and the appliance is ready to make coffee again.

when the display says "Descale" it means that the machine wants to run a cleaning program to remove any limescale build up on the heating elements.
you will need to put a descaleing solution in to the main water tank and run the descale program
follow the instructions in the manual to descale
Note (useing anything but the recommended descaler may void the warranty)

THIS INSTRUCTIONS ARE FOR THE MIELE CVA 615,

The coffee system must be descaled regularly. The time period depends on
the water hardness set. The appliance will display a reminder message and
will eventually lock if not descaled. The message window will first display:
"DESCALE AFTER COFFEES: 100".
This message will appear until the appliance is descaled or locks. When
the count is down to zero, the appliance will lock and the message
window displays: The appliance can only be used again
once descaling has been performed. Let the machine cool before
descaling. Remove the sleeve of the steam nozzle to avoid damage from
the descaling agent. Only use the enclosed descaling tablets for descaling.
The descaling tablets are specially designed for descaling this coffee
system. Other agents may damage the machine and affect the taste of
the coffee and hot water. The descaling tablets can be purchased
from Miele.
To prevent damage to the exterior of the machine wipe up any descaling
solution spills immediately! Add 2 liters of water to the water tank. Dissolve two of the enclosed
descaling tablets in the water.
^ Close the water tank and insert into position.
^ Close the door. The descaling will take place in the
automatic descaling program.
Automatic descaling
^ Turn the program selector
counterclockwise to the "Program
mode" position.Press e, to select "Descaling" with the asterisk. Press ENTER.

Go into your menu and scroll to signal descal, enter, choose "YES" and push enter, then exit and it should be gone and it will come up when it needs descaling again.Also change you water hardness to 4 if you want your machine to last a long time.

If you have a display that says "Decalicify machine" mdo this. To automatically descale your machine, press the scoop button and hold it down until you enter the menu. Use the arrows on the left to scroll down until you come to Descale. Press enter and the machine will enter the mode to descale your machine. The process takes about 45 minutes. You don't have to do a thing except mix a full water tank with descaling solution and have a container under the steam wand when your start. It must be large enough to catch all the water in the tank. To start the descaling process, simply turn the steam knob. When the process is over your machine will say "Descale finished". Remove your water tank and rinse it out. Refill it with fresh water. Replace on the machine and start the descaling process over again to rinse your machine. Go back into your menu and scroll up or down 1 to signal descale and enter. Choose "Yes" and push enter so the machine will tell you when you need to descale again.

make sure the * is on the descaling line

With the selector buttons find Descaling and press OK
This process takes about 35 minutes

1. Empty the water tank, drip tray and grounds container.
2. Insert tray and grounds container, refill tank with with 0.5 Lt. of water and add descaling agent (not the pill or powder used for clean cycle) to tank. Make sure its completely dissolved.
3. Place a container or cup under the steam wand large enough to hold 0.5 lt.

Display says Descaling and press OK
4. Press the water button

Display says Descaling in Progress
after the descaling agent is exhausted

Display says Empty Drip Tray and Spent Grounds
5 Also remove rinse and refill the water tank to Max line
6. Press the water button again

Display says Descaling in Progress
after the machine stops
7. Empty the drip tray and spent. ground container and replace
Display says Rinse Press OK
Display says Appliance Ready

In essence go to Descaling Press OK and follow the directions as they are displayed.

You have to buy descaling tablets from miele.  You turn the knob to program mode and keep pushing the enter button until you get to descaling.  You put two descaling tablets into your water reservoir and replace into unit.  Put containers under the steam valve and the hot water wand. Press enter.  Turn steam valve al the way on.  Keep an eye on the containers.  The process takes about 30 to 40 minutes.  The message will appear 'Descaling finished." Turn steam selector to O and press enter.  Display will read "rinse machine, fill watertank.  Fill tank and return to machine.  Place empty containers beneath hot water dispenser and steam nozzle again and turn steam selector fully on. Allow water to run through system completely.  When process is finished, display will read "Rinsing Finished."  Turn steam selector to O and press enter  Program selector is on Program Mode and display will read Descaling, Timrt, unit is no descaled and ready to use.  Turn program selector to on.

You need to descale the machine with descaling solution.
look at following link for instructions

DELONGHI

I had the same problem with a Saeco Royal Digital. I ran the decalcifying liquid through the machine with the automatic descaling program as per the instructions on the bottle and the DECALCIFY message stayed up.
I solved it by going to the menu and selecting "Signal Descal." and toggling it from No to Yes. I escaped back to the menu and git the usual "Select Product".
Hope this helps.