Subpoena of bank records in a foreclosure appellate case.

My house was sold in a foreclosure sale in 2012 after my case for unlawful foreclosure was lost at the demurrer stage. I am now arguing Glaski on appeal. The Opening Brief was filed, response was received and so was the Appellant Consolidated Reply Brief was filed. Now awaiting court date. Even at this late stage, I wish to subpoena some bank records. I know that they cannot be introduced at the oral arguments but this information would be crucial to my case if it is referred back to the trial court. Is there any reason why I cannot subpoena the needed info. at this stage? Thanks for your responses.