Did you have a previous version of NI-DAQ installed on the computer? If so, I would advise to uninstall all NI-DAQ occurances on your computer, and delete the registry entry and then reinstall NI-DAQ 6.9.1. You can get to the registry entry by clicking on the Start button then goto Run. Type in regedit to open the registry editor. Follow this path: HKEY_LOCAL_MACHINE >> Software >> National Instruments >> NI-DAQ. Delete the NI-DAQ folder, then reinstall.
If you still have problems, try creating a new virtual channel and open up one of the analog input examples to test it out. Let me know if you are not able to get it to work.
Brian