Error in tags not visible at first

I tried to report a bug and followed these steps:
1. Clicked on the Report A Bug button.
2. Filled in the Summary and submitted it.
3. Reviewed the possible matches, and clicked No, I need to report a new bug.
4. Filled in Further information.
5. Clicked Extra options.
6. Filled in tags and used a tag with an underscore. For example: foo_bar.
7. Clicked Submit Bug Report.

At this point, I came back to the list of possible matches with "No, I need to report a new bug" at the bottom. No error message was visible, and the Further information field was not shown. I wasn't really paying attention, and I assumed the bug had been reported. It was only when I went to check on it the next day that I realized it had not been submitted properly.

At this point, I had to retype the bug description from memory. When I resubmitted the bug, I got to the same response, and then clicked No, I need to report a new bug. Only after I clicked that, did I see a general error message and the bug I had tried to submit. When I clicked on Extra Options again, then I saw the detailed "'foo_bar' isn't a valid tag name..." message.

I think that if there is an error with the bug report, you should display the error message clearly and let the user fix the problem.

Once the user has said they definitely want to report a new bug, I wouldn't show the list of possible matches anymore, but that's a minor thing.

All of this is taking place on:
https://launchpad.net/launchpad/+filebug#form-start