Actually you need to make the scanner make aware of the new script. GSA is the web interface and simply shows what is collected in the database. See here for an overview how the modules relate to each other:
If you enabled signature checking for your setup, then you need to establish trust for your own scripts or else they will be ignored:
You need to use a OID out of a special range to prevent collision and you should place them into the “private/” directory to not let it be removed during feed sync.
Please check the log files for any problems with the scripts. The following topic might help with resolving any problem: