S60R Rear Calipers Can't Fit On 850R Volans ?

3 days ago I tried to fit S60R rear calipers to 855R Volans,but failed,I've bought iPd adapters,what's the problem?offset? spacer required??

I've read about this  

http://www.volvohowto.com/how-to-fit-s60r-rear-brake-calipers-to-an-850-s70-v70-or-c70/

is it volvo V70R 17" pegasus or ipd replica ones?

I originally thought I could fit perfectly with 855R volans......badly..