Hi Steffen,
this is a known problem with DAQmx 8.7.(1) . It should be solved in version 8.8 and above.
Currently you can downgrade to DAQmx 8.6.1 driver.
To remove DAQmx completely goto System Control -> Software -> National Instruments -> Add/Remove and remove:
- NI-DAQmx 8.7.1
- NI Measurement & Automation Explorer 4.x
- Traditional NI-DAQ
After that you can install DAQmx 8.6.1:
http://joule.ni.com/nidu/cds/view/p/id/950/lang/de
Good luck and a sunny afternoon.
Ralf N.
Applications Engineering
Germany