Joomla 1.5 and Mobile Joomla!

Hi.
It is compatible with Joomla 1.5, right?
I installed it on, but it still displaying PC version. I havent changed anything after install!
But when I tried it on 1.7, and also didnt changed anything, it worked.
What might be wrong?

Got it.
I installed before Mobilebot, and I had disabled it. After installing Mobile Joomla (it uses same thing, if im right) it still was disabled.