In the Ctrl+M window you have to choose which AXIS to rotate around, X, Y, or Z.
If you are rotating a ladder, you want Z.
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OR you can use the Selection Tool (Shift+S) to rotate. You already use it to move stuff.
Just click on an object until you get circular handles. Drag them to rotate. Hold SHIFT and it will only rotate 15 deg. at a time!! Neat!!