reinstalling application problem in android

I try to use reinstall a application that I made in android. but, istalliation doesnt complete, it s not installed. after I uninstall application that in device, than, I try again to install same application. in this time,开发者_Go百科 it s intalled.

what may be to block reinstalling a application ?

it s about signature problem. after I look detail, even application is same, but their signature is different. so, overrite is not finished. the signatures must be same, if you update a program.