Hello Sandeep-
The -10401 error usually results when the configured device number conflicts with the number you try to address it from in your LabVIEW program. To verify the device number, open MAX (Start>>Programs>>National Instruments>>Measurement and Automation) and expand the Devices and Interfaces>>Traditional NI-DAQ (Legacy) folder. The device number associated with your device will be listed there. You should then check your LabVIEW program and make sure that all instances of "Device Number" input match the configured number in MAX.
If you still experience problems please let us know a bit more about your application. Specifically, what type of DAQ card are you running and what is it being used for in your application. If you're running an example program please post that as well.
Hopefully this helps-
Tom W
National Instruments