Bug Installing App without _DEBUG in file name

i.Initialize(i.ACTION_VIEW, storedFilePath & appName)
i.SetType("application/vnd.android.package-archive")
StartActivity(i)

This code works if the application to be installed has _DEBUG in the name.
But, it fails with a parse error at StartActivity if the _DEBUG is removed from the name.
This happens with the same exact apk file no matter if the app executing is either a debug version or a release version.

Any thoughts?

The problem is somewhere else.

Try to manually uninstall the app from your device.
Are you signing the app with a private key?