Aren't you forgetting something? Where is your schematic? Where is the detailed photo of your setup?
Pulling 16V down to 5V with a linear regulator is wasting a LOT of power, which means the 7805 will get VERY hot. I hope you have it on a very large heat sink with a fan blowing across it.
Have you probed around your circuit to measure the power rails? As Dave Jones of the EEVblog always says, the first commandment of electronics troubleshooting is "Thou shalt check voltages".