Since you know that Normalize Waveform.vi is inside the Express VI, you have apparently converted Play Waveform.vi to a standard VI and opened its block diagram. You can either remove Normalize or, probably better, add a boolean control and a case structure around Normalize from the Play Waveform and save with a different name.
While you are at it, change the signal inputs and outputs to arrays of waveforms (as it uses internally) and get rid of the evil Dynamic Data Type. You can use the process to teach your students better programmig pracitces while getting the Vi to perform as you want.
Lynn
