On some Ladders the members of that Ladder decided to have the option of formal challenges put up for a vote. If the majority of the Ladder members voted to eliminate the system from their Ladder, then it was removed. If the Formal Challenge System doesn't work on your Ladder, the Ladder members most likely voted to remove it from your Ladder. Check with one of your LadderOps to verify whether or not this is the case.
If you experience this bug, please visit the “Support” link, submitting a mail with a detailed explanation of what the problem was. This will help us to get the kinks worked out as quickly as possible. Thanks!
Regular challenges are issued in live chat when you run into someone you want to play a Ladder match against.
The Formal Challenge System is in place so that if you are having a hard time finding someone you want to challenge you can do so through the website with our support. You should always try to get your match through the normal methods first before resorting to issuing a formal challenge.
Formal Challenges are satisfied by playing a normal Ladder match using standard Ladder rules or by playing a tournament match if the tournament is a LadderStats tournament.