Brother mfc-9840CDW waste toner box replaced but error message continues

According to the brother support web site the printer should detect the new waste toner box.
However if it does not detect it you may need to clean the contacts
see
https://support.brother.ca/app/answers/detail/a_id/134713/~/how-do-i-clear-the-message-replace-wt-box%3F
for more details explanation of issue

The message 'No Waste toner box' indicates the belt unit is not installed properly. To verify the belt unit is installed properly, follow the steps on this link:

https://help.brother-usa.com/app/answers/detail/a_id/76056/~/how-do-i-clear-the-message-no-waste-toner%3F

If the problem continues, the printer may need service. The printer has a one year limited on-site warranty. If the printer is in warranty, call Brother Customer Service at 1-877-Brother (1-877-276-8437) for warranty options.



If the printer is out of warranty, contact a Brother Authorized Service Center for repair by clicking on the link below:

http://www.brother-usa.com/service/default.aspx

The 9840 uses a WT100CL cartridge for collection of Waste Toner.

If you remove the Drum Unit then the Plastic Sheet (Transfer Belt) like thing the Waste Toner sits underneath this. Lift out the waste toner and replace it or put one in if it is missing.

Put the Transfer Belt and Drum Unit back in. Close the machine and away it goes again.

Waste toner box doesn't require resetting and cannot be reused.
Try to take it out and install again.

The waste is captured more for easy, clean and safe disposal. As far as operation ogre the printer you could empty the waste and RE use the bottle.

The manual for that product can be found here: http://welcome.solutions.brother.com/bsc/public/us/us/en/doc/manual_index.html?reg=us&c=us&lang=en&prod=mfc9440cn_all&dlid=&flang=English&type2=-1
You need to replace the waste toner box.The process of doing this is a little complicated so I would look at the manual which includes illustrations on each step. The section you are looking for is called "Replacing the waste toner box" and it can be found in appendix C under replacing the consumable items.

1. 2. -> unscrew

shake to empty
http://s14.directupload.net/images/130409/awjs9m88.jpg

You could try resetting the toner cartridge settings. OPen the machines front door where you would replace the cartridges. On the top panel you will see a "clear/back" button. Press it and on the display you will see a reset menu come up. Arrow to each one and hit the OK button. Press "1" to reset. Once you have gone through all close the front door of the machine and press stop to bring the display back to normal.

Hope this helps.