Sadly this is one of those situations that while it pertains to real estate is actually a tax questions. Call your accountant and ask - they are the only ones allowed to interpret the IRS tax code.
Also, you are talking about $6,500 tax credit. That was the amount for selling a property THEN buying. The tax credit for purchasing your first home (first in 3 years) was $8,000. To get the $6,500 you would have had to sell first and purchased before the deadline, since your other property is still for sale you did not make it in time.
You can refer to this website for some additional information: http://www.federalhousingtaxcredit.com/