Under the channel it says SAP and no sound comes out on some channels,on other channels its says stero and works fine how can i fix the problem

I found this information in the manual, and perhaps it will help:

1 Switch the audio.

• Every time you press [AUDIO], the audio will

be switched as below.

MAIN : Outputs main-audio

SAP : Outputs second audio channel
MONO : Outputs mono-

Also the manual says this about SAP:

SAP

(Secondary Audio Program)

Second-audio channel delivered

separately from main-audio channel.

This audio channel is used as
an alternate in bilingual broadcasting.

Here is a link for the manual, in case you want to go over the settings. I'm thinking this is a setting problem in the menu, but it can be a physical problem with a cable line.
http://dukeelectronic.com/Manual/IWT3206.pdf
Of course it could also be a trickier problem, but check your settings, check the cable line with another TV if possible, and then contact ILO Support for help, in the event nothing fixes it.
Good luck, and hope this helps.