Label Graph Widget DataField Binding Type

Hello,

I am trying to make a dynamic Label Graph (one that can be made without using a set datashape due to variable results for column names) and I am trying to bind the first Field name in an infotable to the first DataField for the Label Graph. I have the service return the name of the first Field Name in the infotable as a string, however it doesn't let me bind this result to the Field Name in the Label Graph.

Thank you,

Mike