Custom Group - Calculated Field - Parameter Not Defined Error

Hello,

I am creating custom group for the description of frozen soils and ice. Within this group I have created several custom headers, for example; Group Symbol, Subgroup Symbol, Ice Structure, Ice Color, etc. See screen shot. 

I am now trying to create a calculated field using these custom headers or parameters. Similar to the calculated StratumDetails - Description that comes with the US Standard configuration pack.

But whenever I try to build an expression with my custom headers I get an error, "Parameter not defined". See example of code below. 

concatenatewith(
      '; ',
      concatenatewith(' to ',[FrozenSoilandIce.IcePercentageMin],[FrozenSoilandIce.IcePercentageMax]),
      [FrozenSoilandIce.GroupSymbol],
      [FrozenSoilandIce.SubgroupSymbol],
      [FrozenSoilandIce.IceHardness],
      [FrozenSoilandIce.IceColor],
      [FrozenSoilandIce.IceStructure],
	  [FrozenSoilandIce.AdditionalDescription],
    )  

Any suggestions is greatly appreciated.