You added post ID (not topic ID).
You need to add topic ID in program for topics (not post ID).
They are not related and completely different.
When viewing sub-forum in that forum -> right click on needed topic title -> "Copy link location" -> it will copy correct URL when which is like this:
Code:
https://gaypower.org/index.php?page=Thread&threadID=18473&action=firstNew
Or you can as well see it in HTML source. Just open HTML source in topic and search for threadID.
I will also improved for next update to find correct topic ID from post URL (you will be able to just enter post URL in topic ID field and it will detect the correct topic ID).