Error message when adding membership

Hi all,

I'm trying to give a membership to a patron who has never had a membership (under the household or individual) and whose gift has been soft credited (in a batch that is closed and posted). This is the error message I receive: 

Cannot add membership because a current membership already exists for this membership organization or there are pending transactions in a controlled batch. 

Any thoughts on what the issue is?

Thanks,

Hoori