REXX DATE function

[Gentry, Stephen]

I am trying to run the following code:
<code>

/*  */                        
date1='12 OCT 2008'           
date2='13 OCT 2008'           
trace i                       
date11 = DATE('B',date1)      
date21 = DATE('B',date2)      
say '-->diff=:'date21-date11-1
exit                          

</code>

When I do, I get the following results:

SRGELAPS

     5 *-* date11 = DATE('B',date1)

       >L>   "B"

       >V>   "12 OCT 2008"

     5 +++ date11 = DATE('B',date1)

DMSREX475E Error 40 running SRGELAPS EXEC, line 5: Incorrect call to
routine

Why am I doing wrong?  HELP REXX DATE shows the DATE format that I am
using to be valid.  I've tried plugging in the actual date (with quotes)
and get the same results.
Thanks,
Steve G.