Screenshot: https://drive.google.com/file/d/0BxMn8--P71I-azFNbl9Ual9RTUE/view?usp=sharing
The contract is to move an existing probe (called "orbit the mun") into a new orbit. The specifications are that the apoapsis should be 558 360 m and the periapsis should be 198 170 m. As you can see, Kerbal engineer puts the probe's apoapsis at 558 387.7 m and periapsis at 198 749.8 m. These should be within the error bounds. You can see in the screenshot that the apoapsis and periapsis line up reasonably well with the target orbit.
It definitely is the right probe because it has the blue square around it and "be in command of orbit the mun probe" is checked.
I've already read other questions like this, and in every case, the problem was going the wrong direction. But here, the descending node is 0 (shown in the screenshot), which means I'm going the right way, right?! The inclination is about 179 degrees, so that means I should be going clockwise, and I am going clockwise. My vessel has been like this for more than 10 seconds.