query error message runtime '3071'

[Bobnz]

This query works sometimes and not at other times.
When it doesnt work the error message is..
"the expression is type incorrectly or is to complex to be evaluated".

SELECT tblworksheet.jobnumber, tblworksheet.clientname, tblproducts.ProductID, tblproducts.ProductName, tblproducts.ProductDescription, tblproducts.SupplierID, tblsuppliers.SupplierName, tblsuppliers.ContactName
FROM tblworksheet, tblsuppliers INNER JOIN tblproducts ON tblsuppliers.SupplierID = tblproducts.SupplierID
WHERE (((tblworksheet.jobnumber)=[Forms]![frmworksheet]![txtjobnumber]) AND ((tblproducts.ProductID)=Eval("[Forms]![tblworksheet]![cmboven].column(0)")));

any help appreciated.

TIA

Bob

 

[BNPMike]

You've got a mix of SQL dialects there. Why don't you develop the query afresh using the QBE screen? It will give you pukka Access SQL.