The problem is that the limit for the lite version is not for just exensions but ANY button type.
When generating the automatic configuration, the buttons are sorted by type:
1 conferences
2 extensions
3 park
4 queues
etc.
As you have many conferences, you fill all the 15 slots with them. If you are using fop2admin, you can disable some buttons by checking the disable checkbox, so, go to fop2 buttons, click the checkbox for all but 2 or 3 conferences, and you will make room for some extensions.
Best regards,
