When I'm having trouble with a regex, I try to use as many different correct variations as I can, and see if any of them work. This helps me to rule out bad escaping and the like as possible causes.

You might try the following:

/\?id\+(\d+)/
/.id.(\d+)/
/(/d{7})/
/.id.([^ ]+)/
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and whatever else you can think of. Try reducing it to the simplest possible regex you can think of that will work, even if you know it won't work in the general case, or even if it isn't as robust as you want it to be.

If not of this helps, it's time to run the debugger on your code and make sure the string is getting read in as you think it should be.

Good Luck,
Mark