#error in calculated field when I use left joint

[masoud_sedighy]

I have queries (query1,2) that there is calculated field in that. Now when I use left joint another table with this query (query2) for some rows that there is no match between them, result query (query3) shows #error in calculated fields please help how I can remove this #error and just shows null in these cases.

Query1:
   
  SELECT Table1.DocumetNo, Table1.Title, Max(Table1.REV) AS RevNum, Max(Table1.DocDate) AS DocDate, Max(Table1.Trans&"\"&Table1.Purpose) AS TransPurpose
  FROM Table1
  GROUP BY Table1.DocumetNo, Table1.Title;
   
  Query2: (Calls Query1)
   
  SELECT Query1.DocumetNo, Query1.Title, Query1.RevNum, Query1.DocDate, Left([TransPurpose],InStr(1,[TransPurpose],"\")-1) AS Trans, 
  Right([TransPurpose],Len([TransPurpose])-InStr(1,[TransPurpose],"\")) AS Purpose
  FROM Query1;
   
  .query3: (calls query2)
   
  SELECT tblDocuments.*, Query2.RevNum, Query2.Trans, Query2.Purpose
  FROM tblDocuments LEFT JOIN Query2 ON tblDocuments.DocumentNo = Query2.DocumentNo;

Best regards

 

[Galaxiom]

IIF(whatever Is Null, Null, {your calculation})