GeneXus - error

[GxFATDataException: GeneXus Fast Access Message: [Microsoft][ODBC SQL Server Driver][SQL Server]No se puede abrir la base de datos solicitada en el inicio de sesión 'Car_Forestal'. Error de inicio de sesión.]
GeneXus.Data.FAT.GxCommand.Close()
GeneXus.Data.FAT.GxCommand..ctor(GxConnection Connection, String objName, String stmtName, Int16 updatable)
GeneXus.Data.FAT.GxDbCommand..ctor(IGxDataRecord db, String stmt, Int16 updatable, IGxDataStore ds, String objName, String stmtId)
GeneXus.Programs.hmantenedor_proveedor.E11032() +298
GeneXus.Programs.hmantenedor_proveedor.ws032() +1428
GeneXus.Programs.hmantenedor_proveedor.webExecute() +54
GeneXus.Http.GXHttpHandler.ProcessRequest(HttpContext httpContext)

[Exception: GXApplication exception]
GeneXus.Http.GXHttpHandler.ProcessRequest(HttpContext httpContext)
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication+IExecutionStep.Execute() +179
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +87
??
que error puede ser ese?????????????