Piezo as sensors with 8051 problem

Hey I am creating a device that will be attached to regular Drum Kit. The setup is quite simple piezos with 1M resistors are plugged into 8051 and from arduino i read each value from the analog input. Everything is kind of straight forward cause I can read from the piezos values, but what I have noticed is that when i hit one piezo, the readings in other inputs are affected as well, and the values are high enough so I cannot from code really say which one was hitted (because I don't really care about what the values exactly are, just one hit). For me it seems that all the line of piezo's connected together affect the rest of the inputs somehow.
I guess I screwed up something with the piezo connection.

Thanks for any kind of hints!

oh and here is the schematics diagram for my connection setup

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1. yeah thats true, i meant 4051!
2. Like i said i can read with no problems at all signal from piezo, and actually the signal is not that short duration, because the piezo resonates for some peroid of time...

i have this mega version of arduino, and i plugged all of them in, and had the same results like i said, i could recive the signal, but it was affecting all the rest of the analog inputs, this is why i considered using 4051 because I was expecting it to have some built in stabilization etc things inside.
Like I said I don't have a problem with reading the signal from the sensor, just one sensor seems to affect the rest of sensors (analog inputs actually)