TLRNDSI fit problem

I finished installing starboard inwale and did a test fit of the TLRNDSI mount and it slopes down from the inwale. How do I make it fit. have tried to add photo but did not work.

Larry

 

Is the thwart mount top face horizontal, or sloping down as it projects inboard?    

   It is sloping down as it projects inward I clamped the mount in place and used a level to check oreitation.

Larry