A few things wrong here:

1. Unusuals above 10 keys need to be rounded to the nearest key, so your range should be 11-13 keys.

2. You can only use sales from the past 2-3 months, depending on how many sales their are.

3. You need to check ALL sales within the timeframe, not just Gladiator sales. Trades between individual users and marketplace sales also need to be checked.

4. You need to provide the items history and compare links showing the trade, or a screenshot of the trade.

I'd highly recommend reading the rules for unusual suggestions before making another suggestion. https://forums.backpack.tf/topic/6033-rules-for-unusual-price-suggestions/#comment-67068