Premade Queue problem?

We have 4 premade.

Our roles are spread evenly - 2 top 2 jung 2 mid 2 bot 0 supp

We couldn't find a game. Basically, the game forces you to have a support in your team. Why can't it just search for someone willing to play support?

Eventually I put fill as secondary, and instantly find a game, putting me support.

Riot. Why is this? We want to find a support to play with us, but instead it doesn't let us search unless someone plays support.

Please fix this.