C program about enhancing speech in wav file

I am trying to analyze a program that enhances speech in a noisy wav file sample
The final result has the correct wav file header and is exactly like the original one
However the final file is a few hundred bytes shorter than the original which I think should be equal in length
However, when I try to play the wav file Windows Media Player says it cannot play this file
What could be the reason?
I can plot both the wav files in Matlab and there is definitely sound in the created file
And since the header is exactly the same as the original shouldn’t it be playable?

There is some detailed information here about WAV format that may help you to find where the difference lies: http://www.sonicspot.com/guide/wavefiles.html