Hello,
The second line of your mathscript is actually performing the waveform generation for you. If you change the output type of b to a 1D array of double, you can wire this directly to the output sound VI. Choosing to have b output as a string causes MathScript to convert the first element of the array (0, in this case) to a character. The ASCII character for 0 is a null character. Consequently, the Formula Waveform VI doesn't have anything to work with.
Grant M.
Staff Software Engineer | LabVIEW Math & Signal Processing | National Instruments