Can't buy keys in CS:GO

[Mostly Peaceful Protests]

Hello. I used my paysafecard on Steam, I got confirmation that everything went well. I see money on my Steam account, but I can't buy anything in CS:GO. Message is:
"There seems to have been an error initializing or updating your transaction. please wait a minute and try again or contact support for assistance".
I make it clear - purchase has been done. I HAVE money on Steam account, but can't use it in game.
Can you help me? I've already sent a question to Steam.

[cSg|mc-Hotsauce]

What does it say here? https://help.steampowered.com/en/wizard/HelpWithPurchase

[Mostly Peaceful Protests]

Ok, problem solved. It turned out my one transaction was doubled. Purchase went normally, I had the money on account, but for some reason another one, identical transaction came and it was pending. I deleted it and problems disapeard.