one click sometimes work as double click and vice versa

I do not notice that after i buy it,

after install ZAGG invisible shield may be some water go in, the one click homebutton sometime work as one click and some time as double click, also when i click double click it work like one click sometimes, that make me hate my iphone, the warranty expired, i confuse when i click one act one sometimes two and when i click two act two sometimes one, how I can fix this issue,

please help ...

Thank you