BS Player Free compatible, BS Player paid isn't!!?

[alpine]

I found some time ago that BSPlayer was the best and would play everything I tried. It also has a nice customisable user interface.
I noticed that the paid version has an audio preamp setting so I've just bought it from the Play store.
It installs OK on my Xoom and on my Huawei phone, but on my Ainol Novo 7 Fire, the play store says incompatible. But I've been running the free version on the Ainol since I got it!
I tried the usual fix, which is to change the screen DPI from the non standard 200 to the standard 160, but the Play Store still won't let me install it on the Ainol. Which I bought for the primary purpose of watching movies via BSPlayer...
Any ideas for a fix please!?
I can send a copy of the build prop file to someone from BSPlayer if it helps.
I tried registering for 'pro' support, but it doesn't seem to know about the Android users.