Referencing a dataset field

Hi guys,

Please see attached print screen. I have an expression to determine whether the first column of a table is visible. I have dragged the field type_id out of the dataset onto the report, so it now exists as a textbox that I am referencing in the top line of the expression. However i'm thinking that this is not required and I should be able to reference the field within the dataset itself (without the need for the textbox)?

Using the expression builder I created '=First(Fields!type_id.Value, "GetType")' which I believe I should be able to use to replace 'ReportItems!type_id.Value' but this doesnt seem to be the case?

Thanks,
Dean
problem.png