Home button not depressing, but works when front is removed?

Hello,

I have an iPod touch 5g which I repaired the screen on, when reassembling I found that the home button seemed jammed, but there is no sign of catching.

when I took the screen back off I can depress the button on the ribbon cable and it works fine, but when pressing the button on the front of the screen it does not even move, can anybody help me with this?

Many thanks,

Tristian.