The Frozen Throne is an expansion pack . It requires the base game— Warcraft III: Reign of Chaos (ROC)—to function. You cannot play TFT with only a TFT key; you need a valid ROC key installed first.
Purchasing from sellers without feedback or a proven track record of delivering legitimate keys can result in losing money or getting a non-functional key. warcraft 3 frozen throne license key
Ensure you aren't confusing "O" (the letter) with "0" (the number). The Frozen Throne is an expansion pack