I'm trying to use mathscript formula to create an audio file and I'm not sure why my vi is not working. It says the data type has to be string but the graph just shows a blank line
Building a waveform from a formula requires special syntax. The mathscript node is trying to output a 1-D array. Rather than trying to fold your formula into something the waveform generator can understand, I recommend just building the waveform directly.
I tested it, and did not get the straight line. Dunno if the sound is working properly, as I do not have a soundcard.