Illegal parameter assignment?

[SeH]

I'm trying to make a simple string comparison like this:

FUNCTION Ok_Att_Aktivera : VOID
    
    VAR_INPUT
        editable_article_nr : STRING[15];
        active_article_nr : STRING[15];
    END_VAR
    
    VAR_OUTPUT
        okAttAktivera : BOOL;
    END_VAR
    
    
    IF editable_article_nr = active_article_nr THEN
        okAttAktivera := TRUE;
    END_IF;
    
END_FUNCTION

But when I try to compile I get two errors both saying "Illegal parameter assignment". It seems like the problem is in the IF statement but I can't figure out way. Does anyone else know what's wrong?

 

[L D[AR2P#0.0]]

Same as before, FC calling FC cannot pass on INPUT parameter of string type. Use temps, but initialise required first.

FUNCTION fc888 : VOID
    
    VAR_INPUT
        editable_article_nr : STRING[15];
        active_article_nr : STRING[15];
    END_VAR
    
    VAR_OUTPUT
        okAttAktivera : BOOL;
    END_VAR
    VAR_TEMP
        sC1:STRING[15];
        sC2:STRING[15];
    END_VAR
    sC1:='';
    sC2:='';
    sC1:=editable_article_nr;
    sC2:=active_article_nr;
    IF  sC1 = sC2 THEN
        okAttAktivera := TRUE;
    END_IF;
    
END_FUNCTION

 

[SeH]

Thanks again