How to add part number in this macro

Hello, I am using this macro by https://www.codestack.net/solidworks-api/document/sheet-metal/export-all-flat-patterns/ to export dxf files. Now I want to add Part Number to the naming to differentiate bodies but it does not work for some reasons (in the file name <\$CLPRP:PartNo> is missing : FileName_FeatureName_ConfName_.dxf).

Here is what I modified : Const OUT_NAME_TEMPLATE As String = "DXFs\<_FileName_>_<_FeatureName_>_<_ConfName_>_<\$CLPRP:PartNo>.dxf"

Is my synthax wrong ? 

 

Thanks in advance