Home appraisal question - posted in OT, better here, I think

I have a game room / pool room that is 500sqft. It is under the same roof as my regular living area but you have to walk through a carport to get to it. It is totally finished, granite, central A/C, and all the same trim as inside. The appraiser basically gave me nothing for it. He counted it as a storage room on his report.

Any appraisers out there? I was told it would at least count as half my normal living, so 250 added to our square feet.