Expression column. Can't use aggregate function.

Hi, When I tryed to create expresion column using some relation navigation ( Child keyword ) , the following exception was thrown : An unhandled exception of type 'System.Data.EvaluateException' occurred in system.data.dll Additional information: Unbound reference in the aggregate expression 'Sum(child.[Cost])'. Could someone suggest how to use expresion columns correctly ?

Did you find an answer to this problem ?. I have a similar problem when trying to use the max function. > Hi, > > When I tryed to create expresion column using some relation navigation ( Child keyword ) , the following exception was thrown : > > An unhandled exception of type 'System.Data.EvaluateException' occurred in system.data.dll > > Additional information: Unbound reference in the aggregate expression 'Sum(child.[Cost])'. > > Could someone suggest how to use expresion columns correctly ?

As far as I can see, you have to add the column 'after' you have filled your dataset. If you try to add it before there is any data, it doesn't like it. Like many things in ADO.NET, it doesn't act nicely, or give you an error message that would give a good clue as to what's going on when it pukes... Tim. > > Hi, > > When I tryed to create expresion column using some relation navigation ( Child keyword ) , the following exception was thrown : > > An unhandled exception of type 'System.Data.EvaluateException' occurred in system.data.dll > > Additional information: Unbound reference in the aggregate expression 'Sum(child.[Cost])'. > > Could someone suggest how to use expresion columns correctly ?

This worked for me. Thanks. It would be nice to know why it fails. > As far as I can see, you have to add the column 'after' you have filled your dataset. If you try to add it before there is any data, it doesn't like it. > > Like many things in ADO.NET, it doesn't act nicely, or give you an error message that would give a good clue as to what's going on when it pukes... > > Tim. > > > > Hi, > > > > When I tryed to create expresion column using some relation navigation ( Child keyword ) , the following exception was thrown : > > > > An unhandled exception of type 'System.Data.EvaluateException' occurred in system.data.dll > > > > Additional information: Unbound reference in the aggregate expression 'Sum(child.[Cost])'. > > > > Could someone suggest how to use expresion columns correctly ? >