Hi, I made a simple mistake when I installed ArcGIS Mobile, you might have made the same mistake as me.
Insert your ArcGIS Mobile CD (or run from ISO) and when you install it you should click on Custom installation and you should see that the SDK may not have been installed.
In this case you have already installed both Desktop and Mobile.
So you will need to insert the Mobile CD, click on Modify, then install the SDK.
Do the Same for the ArcGIS Desktop Cd, click on Modify.
If for some reason you don't see this option. Go to Control Panel > Add/Remove Programs (Depending on OS) > Click on ArcGIS Desktop or Mobile > Change > Modify (make sure CD is inserted).
Click custom installation and install the SDKs for both Mobile and Desktop (to get ur ADF).
Do the same for the ArcGIS Server.
If you have further questions please let me know.