Dear Sir,
Please make sure that when you call the function in VB you are using the correct Axis resource number. Also check that the Axis that has the DAC you are calling is not configured to be a Servo axis. When manually manipulating the voltage output of a DAC it should not be configured to be a Servo type of axis. Your Flexmotion Software Reference Help Manual can provide you with suggestions, resources and error codes.
Error -70006 is related to a bad resource error. So please check out this suggestions. Good luck!
Regards,
Nestor S.
Nestor