Sorting in Design Pattern Framework 4.0

Hi am using V4 and have a question on sorting.

Lets say we have an entity of Employer which has LastName but my class Employer has it as Surname, The Framework works using the Mapper classes and converts Employer.LastName to Employer.Surname for CRUD, However as the sorting is handled by string values the UI would pass to service SortExpression 'Surname ASC',  This will fail as sorting with the dynamicLinq class parses the string to find the value Surname but the entity cannot by sorted as it expects LastName.

Am I missing something or is it an issue that needs refactoring?

Regards Owain