%TRIMR on return value from Proc not compatible

I have a procedure that returns a character value.
I attempt to use %trimr() on the returned value.
The compiler says: RNF7421 Operands are not compatible with the type of operator.

The compiler shows the error is on the %trimr(getProjTypeName(glb_projType))

Code:

workBookName = 'FinancialProjections_' +
%trim(glb_tradename) + '_' +
%editc(nMarketingPeriod : 'X') + '_' +
+ %trimr(getProjTypeName(glb_projType)) +
'_' + %char(%timestamp()) + '.xls';

dcl-proc getProjTypeName;
dcl-pi getProjTypeName char(12) ;
in_projectionType like(glb_projtype);
end-pi;

if in_projectionType = aProjtype_WEB;
return 'WEB_ONLY';
else;
return 'Non_Web';
endif;
end-proc getProjTypeName;

We are at V7R3.

I am feeling a bit dull right now.

Paul

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