Start Here first in search of an answer based on the I.R.S. guidelines.
http://www.irs.gov/newsroom/article/...204671,00.html
You may be able to get the $6000.00 or even the $8000.00 dependent on your filing status from 2001 up till 2009.
Such as Married Filing Seperately and did you claim any expenses on the home (House A)?
2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009.
Was your name on the Mortgage Contract and did you file Jointly on any of those years?
Distance from House-A to House-B.