I thought I knew how %dec worked

Morning everyone

Like the subject says, I thought I knew how %dec worked
Here is my code

d Bxwegt s 5 inz('01800')
D Bywegt s 5p 2
*-------------------------------------------------
* Stand Alone Fields - BOTTOM
*-------------------------------------------------

**************************************************
/FREE
Bywegt = %dec(Bxwegt: 5: 2);

*inlr = '1';
return;
/END-FREE

Pretty simple and straight forward, but when I run this, I get the
following error message
Message ID . . . . . . : RNX0103 Severity . . . . . . . : 99
Message type . . . . . : Diagnostic
Date sent . . . . . . : 11/10/10 Time sent . . . . . . :
13:00:14
Message . . . . : The target for a numeric operation is too small to hold
the result.
Cause . . . . . : An arithmetic operation resulted in a value which is
too
large to fit in the target. If this is a numeric expression, the
overflow
could be the result of the calculation of some intermediate result.
Recovery . . . : Either make the target of the operation larger or, if
in
an expression, choose the precision of the operands in the expression so
that intermediate value will fit into the intermediate result.

I increased the field Bywegt to 6p 2, with the same result

Am I missing something?
Oh, before I forget (like I almost ALWAYS do) we are at V5r4

As always, any and all answers MUCH appreciated


Alan Shore
Programmer/Analyst, Direct Response
E:AShore@xxxxxxxx
P:(631) 200-5019
C:(631) 880-8640
"If you're going through Hell, keep going" - Winston Churchill