Help!

What am I doing wrong?

"SELECT tblInvoiceHdr.InvoiceNumber, tblCustomers.CustName," & _
"tblInvoiceHdr.Date FROM tblCustomers RIGHT JOIN tblInvoiceHdr ON " & _
"tblCustomers.CustNumber = tblInvoiceHdr.BillToNumber " & _
"WHERE tblInvoiceHdr.Posted <> 'Y' ORDER BY tblInvoiceHdr.InvoiceNumber;"


It works fine until I put the Where tlbInvoiceHdr.Posted <> 'Y'. But I need to narrow the search using this data selection.

"WHERE tblInvoiceHdr.Posted <> 'Y'" will not select records where that column is NULL.

Thank You...I changed to ..."WHERE tblInvoiceHdr.Posted Is Null" and it works fine.