speaker not working after changing the power flex

Hi folks

I have replaced the power flex on a 4s but now the speaker don't work. Any ideas what the problem could be?

I haven't damaged the speaker the only thing I did was peal it off the old power flex.

I thought possibly the speaker was sitting lower and not touching the mother board so propped it up a little but still not working.

This is the second time this happened to me, the last time i just put a new speaker in and it worked perfect.

thanks in advance