error -50103. occurred when I am trying to read to measure two analog channels.

[lawsberry_pi]

  I have a NI USB-6366 DAQ, and I used two different physical channel which are Dev1/ai0 and Dev1/ai1 to collect data in parallel. However sometime ai0 channel DAQmx start task generates the error -50103, and sometime the other channel generates the error. These two channels never both work at the sametime, here is a picture of my code, please help me to solve the problem. Thanks very much  

[RavensFan]

Try searching the forums for the message before posting.  Search "error 50103".  You'll find hundreds of threads that will tell you the answer.