Hello,
Thank you for contacting National Instruments.
It sounds like you are trying to access resources which are already in use by you main VI. If you have a task running which is performing analog inputs (AI) and you try to open another task doing AI (even on different channels), this error will occur.
Please see the following Knowledge Base for more details: http://digital.ni.com/public.nsf/websearch/04BEDD9E9E91ED3486256D180048116D?OpenDocument .
Let me know if you have any further questions.
Sincerely,
Sean C.
Applications Engineer
National Instruments