Bring up the equations window and add an equation.
Double click on the mate that should be driven in the feature tree. Its dimension will appear in the model window.
With your cursor in tthe add equation window, click on the driving dimension. It should add something like "D1@Distance28" to the equation window.
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Double click on the driving mate, put your cursor back in the equation window, then click on the driving dimension.
If you rename all of the associated dimensions and mates it will be easier to keep track of, and it will avoid unexpected behavior if one of the mates gets deleted. Make sure your references flow up the tree.
Michael,
If you rename all of the associated dimensions and mates it will be easier to keep track of, and it will avoid unexpected behavior if one of the mates gets deleted. Make sure your references flow up the tree.