When turned off, your in-game Steam Overlay causes your micro-transaction purchases to fail. To turn on the Steam Overlay:

1. Go to Steam on the top hotbar.

2. Select Settings.

3. Select the In-Game tab, and then turn on Enable Steam Overlay while in-game.

To learn more about Steam Overlay, check out Steam Support.

Purchases within the in-game store require you to confirm your selection before completion. This error message may appear if:

1. You cancel the purchase before it completes.

2. You experience any kind of service interruption during the purchase process.

There's a limit to the number of times that you can purchase some in-game store products. Some examples of these limits are weekly purchase limit, and single, one-time only purchases. If you try to make a purchase that falls outside these limits, you'll get the error message.

This error message appears anytime your purchase exceeds the funds in your Steam Wallet. To add funds to your Steam Wallet:

1. Open Steam.

2. Log in to your Steam account.

3. Click your profile name, and then select Account Details.

4. Select +Add funds to your Steam Wallet and then select an amount to add.

5. Proceed to checkout.

For more information about adding funds to your Steam Wallet, check out Steam support.