Is there any reason why I COULD NOT call in wkD15-007 Agent 37 with the Nightwing ID card? His character card has no real name.....

That would be why.

Character name needs to match the ID character name or the real name needs to match the real name.

Agent 37 matches neither (because he has no real name).

Is there any reason why you think you could call him in?

It's a simple enough answer from a rules point of view, you pretty much answered your own question in a way and Wolverazio has already given you the correct ruling. But and I'm not an expect on comic book history by a long way and I know it's a bit dodgy using comic book logic to justify heroclix logic however if it helps to rationalise the rule wasn't Dick Grayson supposed to be undercover when he was agent 37? If so from a comic viewpoint as well it makes sense that he couldn't be called in with the Nightwing card, though of course the real answer is as already stated by Wolverazio he doesn't match name or real name.