SQL If Statement in Access Query

I'm not sure what I am doing wrong, but here is my SQL Code within my Access Query:

SELECT Count(qryVendorX.[Item #]) AS [TotalItems]
FROM tblItemMaster RIGHT JOIN qryVendorX ON tblItemMaster.[Item #] = qryVendorX.[Item #]
GROUP BY qryVendorX.VendorNumber, qryVendorX.VendorName
HAVING (((qryVendorX.VendorNumber) = [forms]![frmPOTransHeader].[Vendor #]))

IIF (qryVendorX.[TotalItems])>0
SELECT qryVendorX.VendorNumber, qryVendorX.VendorName, qryVendorX.[Item #], tblItemMaster.Description, qryVendorX.[Vendor Item #]
FROM tblItemMaster RIGHT JOIN qryVendorX ON tblItemMaster.[Item #] = qryVendorX.[Item #]
GROUP BY qryVendorX.VendorNumber, qryVendorX.VendorName, qryVendorX.[Item #], tblItemMaster.Description, qryVendorX.[Vendor Item #]
HAVING (((qryVendorX.VendorNumber)=[forms]![frmPOTransHeader].[Vendor #]))

ELSE
SELECT tblItemMaster.[Item #], [Department] & "-" & [Account] & "-" & [Sub-Account] AS [G/L Account], tblItemMaster.Description
FROM tblItemMaster
ORDER BY tblItemMaster.Description;

My goal is to display a list of items specific to vendors if the information is in the Vendor Cross Reference Table.  If the Vendor is not in the cross reference table, just display all Items.  Any help is greatly appreciated.

Paula