[Q] mock GPS on GPSless tablet

hello,
my company got us several cheap Genesis GT-8230 tablets ( Andoid 4.0.3
kernel 3.0.8+ build A802HW.A10AAAAAAZAXXXA.RB1.V106.20120804 ) tablets for use on testing and quality control. Those came without a GPS receiver. now they want us
to test a GPS enabled app. We tried to install Mock GPS on those
tablets, but it does not work. Afer downloading the APK we get a " X Applicatin
not installed error". Any hints on that?
thanks,
F