What is the file name of the assembly? If the file is VisitorManagement.dll, the second Configuration should be OK. It looks like a class mapping is referencing the wrong assembly name.
Quote:
NHibernate.MappingException: persistent class VisitorManagement.BusinessObjects.TblAuthorisationLevel,VisitorManagement.BusinessObjects not found ---> System.IO.FileNotFoundException: File or assembly name VisitorManagement.BusinessObjects, or one of its dependencies, was not found.
The mapping should be "VisitorManagement.BusinessObjects.TblAuthorisationLevel,VisitorManagement" if the file is VisitorManagement.dll.