Competitor field unresponsive

Dear creator

Let me start by saying your plugin is what I need. However, I am incapable of making the competitor function work. That is I have made both members and competitors, yet it does not create a list of matches (league) and if I try to add a match manually, I cannot select any of the competitors I made.

I hope you can help.
Cheers.
Kim ??

The page I need help with: [log in to see the link]