This only happens to me when i try to get to moho

When i try to get to moho using mechjeb it screws up. i retro burn until im lower than moho's orbit then i circularize there. Then i tell mechjeb to transfer to moho and it moves to the injection burn point and starts burning but when it stops and says moving to mid-course corrections point or whatever i notice that my periapsis is not even close to moho's orbit.