Bottom Bracket/Hollowtech II problem?
 

I have a new mtb frame and someone was asked what size the bb was. Bike has not been built so I measured the ID of bracket and it was apprx 33.75mm. So I decided to check the Shimano Hollowtech II bearings and I could not get cups to thread into bracket, on either side. Measured the OD of bearing cups and they seem to measure out to about 34.50mm. Could I be doing something wrong, threads look fine on frame, looks like mfr even faced the bracket. Bearing cups are also marked L and R and show direction of rotation to tighten. So I am sort of puzzled. I do plan to have a pro build up my bike as soon as I receive all the components. Thanks,