You are challenging a clan.  In order for the challenge to be valid your clan must:

1. Be 3 or less ranks under the team you are challenging on the LANclub Ladder.
2. Have not had a match against the team you are challenging in the last 2 weeks.
3. Not be in the middle of a challenge with another clan.

The team you are challenging must accept your challenge in 72 hours or file an exemption.  If they do not, then you will win by forfeit.