Troubleshooting MS error message

I am using Access 2007 and have almost completed a database that includes a cross-tab query and corresponding report.

I made some changes to this particualr query and now when I try to run it, I get the following message that I can't decipher,

"This expression is typed incorrectly, or it is too complex to be evaluated. For example, a numeric expression may contain too many complicated elements. Try simplifying the expression by assigning parts of the expression to variables."

Here is the SQL for it,

PARAMETERS [Forms]![frmA]![txtEndDate] DateTime;
TRANSFORM Sum(qryUnionQueryTransactions.PlannedQty) AS SumOfPlannedQty
SELECT qryUnionQueryTransactions.FormattedCostCode, qryUnionQueryTransactions.type, Sum(qryUnionQueryTransactions.PlannedQty) AS [Total Of PlannedQty]
FROM qryUnionQueryTransactions
GROUP BY qryUnionQueryTransactions.FormattedCostCode, qryUnionQueryTransactions.type
PIVOT "Dates" & DateDiff("d",[TransDate],"Forms!frmA!txtEndDate") In ("Dates0","Dates1","Dates2","Dates3","Dates4","Dat es5","Dates6","Dates7","Dates8","Dates9","Dates10" ,"Dates11","Dates12","Dates13","Dates14","Dates15" );

My goal is to have a dynamic cross-tab query/report where all dates are produced as the headings, every time.

Any help would be greatly appreciated.

Any help would be greatly appreciated.