Hey mohowski,
Thanks for contacting National Instruments support. I'm not sure why this would happen. I attempted this myself, and here is the resulting vi. I also am attaching a subvi that I used. Go ahead and run the Cont Gen Voltage Wfm-Int Clk.vi, but be sure to save the second vi on your desktop along side that vi first.
Let me know if you have further questions.
I don't normally just post code, but this question seemed best answered in that manner since you didn't specify exactly how you were attempting to program this application.
Regards,
Kenn North
Principal Product Manager - Search, Digital Analytics
http://ni.com/search