Issue with text mode syntax in a view with a simple subtraction formula

I am trying to subtract a system property call {estimate} and a custom field called Actual Points.  Both properties display correctly using these 2 text mode pieces of code:

displayname=Actual Points
linkedname=resolveProject
namekey=view.relatedcolumn
namekeyargkey.0=resolveProject
namekeyargkey.1=Actual Points
querysort=DE:resolveProject:Actual Points
valuefield=resolveProject:Actual Points
valueformat=customDataLabelsAsString

aggregator.displayformat=val
aggregator.function=SUM
aggregator.namekey=estimate
aggregator.valuefield=estimate
aggregator.valueformat=val
displayname=Agile Assigned Points
linkedname=direct
namekey=estimate
valuefield=estimate
valueformat=doubleAsDouble

But I can’t figure out why I get a blank column when I try to subtract them using this syntax:
displayname=Difference +/-
linkedname=resolveProject
namekey=view.relatedcolumn
namekeyargkey.0=resolveProject
namekeyargkey.1=Actual Points
querysort=DE:resolveProject:Actual Points
valueexpression=SUB({estimate},{DE:resolveProject:Actual Points})
valueformat=doubleAsDouble

Thanks in advance for any and all assistance.