I am getting "Sage.Peachtree.API.Exceptions.IncompatibleCompanyVersionException: Company requires conversion"

I have upgraded my Sage 50 US 2013 to 2015. When I access the Sage 50 Company via the SDK for Sage 2015 (.NET application), I get an error  "Sage.Peachtree.API.Exceptions.IncompatibleCompanyVersionException: Company requires conversion". Can you kindly help me to sort this out as it's really embarrassing.