Whyte T-129 Rear Derailleur Help

kev36uk

I picked up a good condition Whyte T129 frame for a friend, I most of the bits and bobs lying about spares or bits from other bikes to make up a bike for him. only thing i've had to buy was a new cassette and rear derailleur.

So got a good deal on a Shimano XT cassette and derailleur both exactly the same as what came stock, 11sp same teeth on the cassette.

However i can't for the life of me get it to shift properly, it sits touching the frame when the lowest gear and hits the cassette on the second highest cog,

I know i am doing something wrong but at my wits end now and can't see what i;ve done. fyi B screw is at maximum