Batch use of MPLAY32.exe

I am trying to write a ‘talking clock’ batch file.

At the appropriate times it calls MPlay32.exe as follows:

mplay32 /play /close 30.wav
mplay32 /play /close 5.wav

(with the proper path specs for the .wav files).

Independent of the order in which these calls are made the first of them is
successful and the second gives a “Media Player cannot open this file…”
message.

The following also gives the same message:

mplay32 /play /close 30.wav 5.wav.

Does anyone have any idea what is going on or, better still, how to fix it?