LEA2 + Tamron 70-200 2.8 compatibility

Hello,

I bought a LEA2 adapter for my NEX5n, to mount my other alpha lens (I also have a Sony A700) on my NEX.

All my alpha lens (Minolta 20 2.8, Minolta 50 1.7, Minolta 100 2.8 Macro) work fine with the adapter except the Tamron 70-200 2.8 that work only in manual focus and not in autofocus.
Do you know if is it normal or have I a problem on my adapter or objective?

Alex.