Manipulator connection crashes

I'm getting a crash in OpenMayaUI.dll after calling finishAddingManips() from within the connectToDependNodes() callback.

I currently have two distance manipulators which map to simple distance plugs. The code almost identical to the sample code from footPrintManip except I have
added a second distance manipulator for a second plug.

What gives?

The stack looks like this:

baadf00d()	
OpenMayaUI.dll!638ec8f2() 	
Shared.dll!6485e9a1() 	
Shared.dll!6484f4ab() 	
Shared.dll!6484e8f9() 	
SNodes.mll!SNavNodeManip::connectToDependNode(const MObject & node={...})  Line 146 + 0x12	C++