Passing variable through URL of admin page

I am working on a custom plugin. I’ve created a top level admin menu item and that page all works. It shows all members from my database, is paginated and has a search feature.

When you click on any member’s name, you then go to a sub-page, which is the edit the record. The id of the record is passed through the URL and I retrieve it by setting a variable to $_GET[“id”]. Easy enough. I have verified that the variable is accessible from the new page by echoing it on the new page.

For some reason, however, once I run my variables through a function, I can’t retrieve them outside the function. They are declared as global within the function.

Even more odd, if I make the edit member screen a js pop-up called from the main plugin screen (where I’m simply pulling up member.php?id=0), the whole thing works! But once it gets called as its own page within the admin interface (with the id passed through the variable), it no longer works. ??

This is probably so simple and so stupid, but I am so stuck!! Please help… I have never made a plugin before and I’m thinking (hoping?) it’s something straightforward that I just don’t know about.

I hope this made enough sense to get some sort of help. Don’t to bore you with code. ??