"You know what I think of Carlos. I would be desperately keen to get Carlos but there are one or two other issues," he said.
"His injury is coming along fine, there is no problem with that. It's just the fact that he's not ready to play right now that would be a definite problem for us.
"He has been here before and he was terrific for us. I don't see any major obstacles in the way at all.
"The only thing we have a problem with is that we need someone to play sooner rather than later," he added.
Rangers face a trip to Inverness on Saturday in the SPL.