Hello Rajesh
I do not have pci-6723, but I have 6722. Unfortunately, Nidaq 7.2 (that came with the card) had a bug in it and you really could not use the card for analog output with LabView. I was told the issue would be resolved in Nidaq 7.3 (just released few days ago, I am yet to receive the updated driver by mail), and retest.
However, I tested the vi (same modified vi, but with 2 channels only) with a card pci-mio 16 E4 (DaqMx 7.2), used channel 0 for continuous generation and channel 1 with dc output, and The vi ran smoothly, did not get any error message.
I am not sure on what the deal with pci-6723. If you call Ni about that, or that an NI application engineer steps in and f
igures that out. If it is an issue with 7.2 (like the case of pci-6722), then you need to upgrade to Nidaq 7.3