I've just built megadrum and already programmed the ICs. But when I connect it to the computer, using SuperiorDrummer sampler, it gets multiple sound, even though no pads are connected to the jacks. The LCD shows that it has some signal coming from the Jacks. I didn't use all inputs: only 1-9.
Here is a picture of how I wired the Jacks. The red wire is ground.

Can someone point it out where is the error?
Thanks,
Francisco.