Put a wheel nut onto the hub and tighten down so the rotor stays in the center and fixed in place. This stops you having to "juggle" both the calipers pads and bolts etc.
Al.

 

thanks for all the replies, sorry havent got back on here, the problem was i was comparing the seat of the right caliper to the left and it didnt look right, i should have just tried to put the caliper pins back in, would have saved me time and lots of cursing. I have done brakes before didnt make sense to me. I didnt remove the cap and I had some fluid come out, I think the dealer over filled