Help with substitutions in a script

[mcbain2279]

I am running a script to do multiple substitutions of text in a global field running fmp 7. I was told that it could be done but I have been unable to get it to run.

My script is:

Go to Record/Request/page[First]

loop

Set Field[completed_template; Substitute(template; "the_item_name"; item_name)]

Set Field[completed_template; Substitute(template; "the_item_id"; item_id)]

Set Field[completed_template; Substitute(template; "the_item_case"; item_case)]

Go to Record/Request/Page[Next; Exit after last]

end loop

item_name, item_id, item_case, completed_template are all text fields

template is text global

The script runs but only substitutes every occurace of "the_item_name" for item_name in the global field and does not substitute either of the two other substitution fields.

Can anyone see what the problem is? Where am I going wrong? Thanks