Hello Kiana,
Sorry for the delay but I was not able to find a USB 6229 to test it.
I agree with you, the NI USB 6229 should be able to acquire up to 32 RSE analog channels and there is not limit for the number of analog input.
I have tested this behaviour using NI USB 6218 board without any problems. See attachment. Could you please tell me which DAQmx driver are you using?
In my opinion, it could be helpful to test your application using DAQmx Driver 8.6.1
NI-DAQmx 8.6.1 - Windows 2000/Vista x64/Vista x86/XP
http://joule.ni.com/nidu/cds/view/p/id/950/lang/de
Please feel free to contact me if you have any questions about this issue.
Regards,
AmirG