no sound volume bar very odd

iv just replaced the lcd and digitizer on i phone 4

iv done this before with no problems

but this time iv come across an odd problem . in that there is no sound coming from the speaker.

iv done the following tests

.phone is not on silent

.rechecked speaker is clean and in place correctly

.upon pressing the home button twice and swiping over the volume bar is unchangeable and is on zero

.iv checked the microphone and it functions normal and also weirdly when pressing the voice activation the speaker works fine.

the earpiece and volume buttons seem ok

the phone works fine with earphones in

any ideas.. im stumped