I am having trouble installing the apk (I've enabled un-verified app sources). This is what happens:

1) I open the apk file from my device storage to install nzb360
2) I accept the installer permissions and hit "Install"
3) The "Installing..." screen then appears (with animations so its not frozen) but never progresses on from there
4) I've given it about 10 mins so far but it still just says "Installing..."

I am using a Samsung S4 Mini with Android 4.4.2 on it.