Left half of screen is black after replacing? Please help!

This is for a Sony Xperia z. The phone wasn't listed on ifixit. Hi my old screen was smashed (but still working) but decided to replace it as I'm semi competent (maybe not) but anyway I've done a few screens before and they have been fine. Anyway after putting the new replacement screen on and putting everything back together I turn it on and the whole lefthand side is black From top to bottom, right hand side of screen works fine and even the touch works on the whole screen. Any ideas? I've reseated the cable several times but no joy.