Hi,

I am trying to group my Crystal Reports 2008 report on the following SQL Expression named %empl  

(
select max(B.`ResultText`)
from TestMainList A, TestResults B
where A.`TestID`= B.`TestID` and
A.`Description`= 'Employee' and
B.`TestDate` = TestResults.`TestDate`
)


However, when I run the report, it gives me the error "Failed to retrieve data from database" and Database Vendor Code -3100.  

The report runs fine if I add %empl to the details section.  It even runs fine if I group it by %empl AFTER first running the report with the %empl expression in the details.  However, when I try to re-run the report, it gives me the error again.  

The SQL expression is error free when I check it.  I am using an Access database, with an ODBC connection.  Has anyone else experienced this?

I did see that database vendor code 3100 seems to refer to a null value somewhere in the database.  Is it possible to add code to the expression to bypass nulls?
 
Thanks!