Since the problem appears to be related to the DMM driver, I would first recommend reinstalling it on the RT controller. If this does not work, the next step I would suggest is reinstalling it on the host computer, then reinstalling it again to the RT controller.
If you are still having problems after this, please post a reply with some more information about what software is on your system (including versions) and we can explore other options.
Best regards,
David H.
Systems Engineer
National Instruments