[jim_h]

They may have an exclusive contract with the company for that position, for a certain period of time.

Or maybe the company name (or contact details) is NOT part of what they will expose to the candidate.

[icambron]

Generally they have a contract that says something along the lines of "if your initial contact with a candidate is through me, then you'll have to pay if you hire them". I think the caginess part is just an extra precaution.