Changed my glass and and bad signal

I recently broke the back glass to my iPhone and decided to change the front and back to blue. Everything was pretty simple and works great except for my reception. It fluctuates really bad. I can have full bars and 3G service for a good amount of time and then it'll diminish slowly or instantly go to no service. Not having service can last for a few seconds up to over and hour. Then it'll instantly go back to full 3G service. What is going on?