Middle part of trackpad unresponsive to 'tap-to-click'

I replaced my MacBook Pro's (15" mid 2012) trackpad after the first one got a crack after a fall, but now the 'new' one doesn't register 'tap-to-click' properly, especially in the middle part of the trackpad. Funnily enough, tap-to-click works in only a small area on the top-right, and bottom-left of the trackpad.

Furthermore I also have no problem with the 'normal' (sound with click) click.

Any idea as to why I can't use tap-to-click in the middle part of the trackpad, is it possibly defective?