I found out what was going wrong.
I have to change the application that was compiling the script.
The script ran fine the way it is.

Thanks for your help

--- In ib-support@yahoogroups.com, "Tobias Giesen"
<tobias_subscriber@t...> wrote:

> Hello,
>
> wild guess: did you try:
>
> (:INVOICE) + 10
>
> rather than
>
> :INVOICE + 10
>
> Cheers,
> Tobias