I was able to make this work with test objects (with and without the quotation marks, by the way). I tried it first with two models on the same object, and that worked. I then created a dummy object and inserted one record. On that record, I changed the Name to match a Name from the original object. The formula did look up the Id from the original object using the Name from the dummy object.
Have you simply listed the contents (Name field, specifically) of each model and verified that the matching names are actually being included in the models? What about Limits on the models? Is the first model perhaps not retrieving the records that correspond to the records retrieved in the second model?
