How do I tag a bitcoin address using my bitcointalk profile?

[medicine]

I can see that tonnes of people have tagged a bitcoin address using their bitcoin talk account profiles https://blockchain.info/tags
When I enter my info into the relevant fields I just get an error message that my "URL contains invalid characters." 
I can see by the profiles listed below that I am entering the exact same URL address format that they did, yet my tag gets denied with the above error message.
What am I doing wrong?

Thanks in advance.

[grue]

I suspect bitcointalk profiles are tagged through a crawler, because my address got tagged and I didn't do anything.