My drums for guitar hero warriors of rock aren't preforming very well.?

Hi I have a drum kit for Guitar Hero Warriors of Rock on the Wii and my drums don't work to well. It started about a week after I got them, so they were fairly new and they are about a month old now. The problem is when i hit the red yellow or green symbol it triggers the blue to hit also. So that means I can't get 100% on easy songs because of that reason. I tried cleaning the the pads with just simple water, that didn't help at all. So if there are any suggestions that could solve my problem that would be great thank you.