How to create a square wave with a dynamic frequency

[NIquist]

You will find a knowledge base article or other help for most of the common error codes in LabVIEW if you just Google the code or error text.

Error Code -200479 When Running a Data Acquisition Program - NI

[Isabelle.eskay]

I have been working with the program and have it functioning. The output frequency that is displayed (on the frequency dial) changes relative to the input and I am able to adjust the square wave, but this is not actually reflected in the output voltage. I am using an LED to test and the output is not changing. The frequency stays the same as the initial frequency selected. I'm not sure if it has to do with the shift registers. Any suggestions?

[Isabelle.eskay]

I have made a couple more adjustments and attached the program below.  I am using a LED to test the output. I believe the problem is that the code is outputting from the first "DAQmx Write", so it is outputting the initial frequency and not changing. The second "DAQmx Write" is in the while loop, but does not actually output anything. I tried moving it outside the while loop but got some errors. Any suggestions?

Thanks.