I was trying to purchase a champion with IP, but the unlock button was greyed out and wouldn't allow me to purchase. This doesn't make sense, since the champion only costs 450 IP, and I have 706 IP. Does anyone have a solution to this? I already restarted the game (running as administrator), and even restarted my machine and that didn't solve it. Please help!

Also, when I do try to purchase the Champion, I am on the classic skin.

I have the exact same problem, a solution would really be nice.

Are you sure you have 706 IP? Especially if you're making multiple purchases in a row, sometimes your RP/IP display does not update properly.

When you go to make a purchase, look at the math right above the grayed out button. Does it add up to a negative amount? If that's the case your IP display didn't update and you have less than the required amount.

Same thing here. I should have 45 points left over with my IP, I'm buying a 1350IP character. Even if the character is around 400, it's still grayed out.

My wife and I are both having the same issue. We are unable to buy any champions, of any cost, with either RP or IP. The unlock buttons in the screen where one chooses which type of currency to use are simply greyed out. We first noticed this issue the evening of the 22Dec.

I have this problem as well. It states that I would have a positive balance but I cannot unlock any champion.

Purchase your champions on the initial page and do not click on them individually and then click unlock. Under each character there is an unlock option; if you click that you should be able to unlock characters.

I had this problem as well now; I didn't earlier when I went to purchase a champion two days ago.

Following Bartonl e Carton's advice allowed me to unlock my champion, however, though.

My bother is having this issue. He wants to buy a champion for 450 IP when he has 600. The box is grayed out completely.

Bartonl e Carton, you fixed the problem! Thank you!!!