Procedure with || concat function

Hi

I'm trying to create a procedure to dynamicly create a string for my BOM

I have created 2 chareteristics to help me with this:

STPO_SORTF wich is a Reference to a table field

AUX_CHAR10 a help char to hold parts of concatenation

my procedure is as follows

Working

$self.AUX_CHAR10 = 'FOO' || 'BA',

$self.STPO_SORTF = $self.AUX_CHAR10

IF($Parent.SPC_RP = 5)

NOTworking

$self.AUX_CHAR10 = 'FOO' || $self.STPO_SORTF,

$self.STPO_SORTF = $self.AUX_CHAR10

IF($Parent.SPC_RP = 5)

It seems as if every time I try to mix in the STPO_SORTF it just ignores my procedure, I have tried to see if this is because there is at type difference between chars but STPO_SORTF = DB field SORTF in STPO(also inherits this) = AUX_CHAR10

I have tried to force longer string than 10 wich produces a 10 char string even if concat is > 10 fx. 'FOO' || 'BAAAAAAAAAAAA' results in FOOBAAAAAA

Does anyhere have a suggestion to what I am doing wrong?