Hi, Thanks for your offer in helping me.
In answer to your questions,,,, the app was copied locally to the nexus to a variety of different folder, using ES File explorer. double clicking or using the install option from within ES the install starts, tell you the usual things it will access, NEXT, it just fails.
I have set the nexus to install 3rd party apps. Not sure where to change options against an APK file.
However this APK installs fine in the primary/first user.
Incidentally i store all my files for everything, on a WD NAS so i access it directly from the Nexus, my HTC phones etc. Also my own PCs. No issues there. This APK file installs on all my other android devices, even my friends Android phones and tablets, who walk in . connect to my wifi network, and copy the Tubemate APK locally, then run it...
It has to be an issue with this second user profile thing. What else can it be.....