You need to have a higher rank to unlock having more characters and lines for signatures. Looking at your BB code it looks like you exceed the number of characters for a Newbie, as the signature you've created would only probably fit on a Full/Sr member in minimum.
- Newbie: No styling (including links) allowed. Max 50 characters.
- Jr. Member: Links allowed. Max 150 characters.
- Member: Unlimited length.
- Full: Color allowed.
- Sr. Member: Size allowed
- Hero: Background color allowed