Reporting Tree stopped working for Report in Management Reporter.
Removed the tree and the report would run.
Go to Configuration Console and look at errors there and found 'the given key not present in dictionary'
Pulled up the Reporting Tree and made a copy of it.
Deleted rows from the tree starting at the bottom until I could get the report to run.
Upon doing the above I came across row 1736 of 4446 in which there was no unit name listed.
opened original reporting tree, and updated the unit name on line 1736 and the report ran.