The apk you create does not install on the phone

[Yoshi (KidKoder)]

Maybe you want to have a look at this:

[Guide] App not open / open button disabled after install

This will happens when you copy your existing project and modify it and when build it shows that app is installed but open button is disabled. This is because of package name. When you build a project by copying it from existing project your apps package name over writtened. Try changing package name. If problem persists then create a new project, copy all the contents from your existing project to new project and build it. It will works.

Yoshi