I used the top button which changes colour when I press it, but the mail does not get signed when i send it. The only way i can get my mail signed is to select it and use the context (right-click) menu. I have tried with Firefox 3.0.5 on Windows also and I have the same problem.

Using FireGPG 0.7 on Firefox 3.0.5 on Linux x86 with Google Apps, I tried "inline" and "sign" but they do nothing when I send the message.