Explinations of error codes can be found in LabVIEW under 'Help >> Explain Error'
When you punch in error -200429 it will return:
"Measurements: Value passed to the Task/Channels In control is an empty string (or I/O control).
The value must refer to a valid task or valid channels."
Open the DAQ Assistant and ensure that you've correctly specified the name of the physical channel on your 9418. You might also open Measurement and Automation Explorer to double check the device name and perhaps run test panels to ensure that you can communicate with the hardware correctly.
Let me know if you still have any problems after trying my suggestions.
Elijah Kerry
NI Director, Software Community