I got this "The Travel Bug you requested does not exist in the system." after submitting some travel bug numbers on the Geocaching website.
One was from a 'dogtag' on a girl's hat at Rock Town, TH9T1D. The other was a sticker on a car/truck, AG62VO.
Any reasons for these not working?

I thought it might be mistaking a one (1) for a letter L (l) but I pasted just what you had and the first one was found.
For the second give it a try with a zero (0) instead of a letter O and I think you'll find it.

It was good hanging out with you at the events this weekend!

thanks, sometimes it's hard to read o/0 and 1/l.
had a terrific time.

Man, oh man, don't I know that. I deal with tech support kind of stuff for work and way too many times I hear someone-s password isn't working - exactly this issue, confusing O/0 and 1/l.