[V8i] Prepend Configuration Variable value failure (via included file)

I have a PCF, some of the lines in it are below:

_USTN_PROJECTNAME= UA008785
PROJECT_STANDARDS = $(parentdevdir(_COMPANY_SERVER))Client_Standards/CPL/$(_USTN_PROJECTNAME)/
PROJECT_STANDARDS_CFG = $(PROJECT_STANDARDS)$(_USTN_PROJECTNAME)_STANDARDS.cfg
%include $(PROJECT_STANDARDS_CFG)

File UA008785_STANDARDS.cfg contains the following:

MS_CELL > $(PROJECT_STANDARDS)Cells/
MS_CELL > $(_USTN_PROJECTROOT)00 - Common Data/Cells/
MS_CELLLIST > $(PROJECT_STANDARDS)Cells/*.cel
MS_CELLLIST > $(_USTN_PROJECTROOT)00 - Common Data/Cells/*.cel
MS_CELLLIST > $(_USTN_SYSTEMROOT)MicroStation V8i (SELECTseries)/System/cell/archpa.cel
MS_DETAILINGSYMBOLS_CELLLIST = $(_USTN_PROJECTROOT)00 - Common Data/Cells/Detailing_Symbols/$(_USTN_PROJECTNAME)_Detailing_Symbols.cel

The problem is the none of the MS_CELL or MS_Cell List prepends work yet the MS_DETAILINGSYMBOLS_CELLLIST assignment does. I can get it to work if I amend the PCF to the following:

%level 4
PROJECT_STANDARDS = $(parentdevdir(_COMPANY_SERVER))Client_Standards/CPL/$(_USTN_PROJECTNAME)/
PROJECT_STANDARDS_CFG = $(PROJECT_STANDARDS)$(_USTN_PROJECTNAME)_STANDARDS.cfg
%level 3

The question is, why can I not include a CFG at project level and set the above variables and have to resort to doing it at user level? I've reviewed a level 5 debug and I can see it process the files yet it just doesn't want to set the variables.