Drazen,
What driver are you using for the data acquisition board? Are you using an NI-DAQ driver from National Instruments, or are you using a driver from MathWorks?
If you are using an NI-DAQ driver from National Instruments, then visit http://www.ni.com/support/daq/ for troubleshooting information. Even if you are not using the NI-DAQ driver, you may want to install it and use it at least to test the card.
If you are using a driver provided by Mathworks, please contact them for support.
Regards,
Chad H.
Applications Engineering
National Instruments
http://www.ni.com/ask