Field is based on Expression & Can't be edited

I have two combo boxes on a subform.  One pulls the Employees list and the other pulls the EmpClass under 200.  Both of the queries that pull the information is updateabel.  

SELECT     EmployeeNumber, LastName, FirstName FROM  Employees ORDER BY LastName

SELECT Trades.EmpClass AS Class, Trades.TradeName FROM Trades WHERE (((Trades.EmpClass)<200)) ORDER BY Trades.EmpClass;

The subform is based on a query that pulls all the timecard daily from the TimeCardDailRQ Function.  

SELECT     *
FROM         TimeCardDailyRQ() TimeCardDailyRQ
WHERE     (DailyID = 2147458498)

TimeCardDailyRQ Function =
SELECT     TOP 100 PERCENT dbo.TimeCard.DailyID, dbo.TimeCard.EmployeeNo, dbo.Employees.Class, dbo.Employees.EmployeeNumber,
                      dbo.TimeCard.EmpClass, dbo.Employees.LastName + N' ' + dbo.Employees.FirstName AS EmpName, dbo.TimeCard.Job#, dbo.TimeCard.JobHours,
                      dbo.TimeCard.Tokens, dbo.TimeCard.PayCheck, dbo.TimeCard.Perdiem, dbo.TimeCard.RepairsHours, dbo.TimeCard.RigName, dbo.TimeCard.RptDate,
                      dbo.TimeCard.WON, dbo.Employees.LastName
FROM         dbo.Employees INNER JOIN
                      dbo.TimeCard ON dbo.Employees.EmployeeNumber = dbo.TimeCard.EmployeeNo
ORDER BY dbo.Employees.LastName + N' ' + dbo.Employees.FirstName

Everyone of these queries are updateable, so I don't understand where I'm getting the Expression error.  If I pull the subform up alone it's updateable.  However, it's  not updateable when it's attached to the parent form.  

Where to I go from here?
Thanks,
SCS1ST