Do you have the LabVIEW Real-Time Module and the Real-Time component of NI-DAQ installed. Most likely, you installed NI-DAQ before LabVIEW RT and NI-DAQ did not install the RT component. You can check this by modifying the installation in Add/Remove Programs and adding the RT component if it isn't present.
Regards,
JR A.
Application Engineer
National Instruments