You will have to wait until someone sells that specific item to the bot,as all of our bots are restocked by users like you.
You can also check the other banking types for your desired item (for example, if you are looking for rare hats or rare stranges, check out item banking)
Then you will have to wait until the bot gains more space by buying or selling (depending on what banking) items from/to the users. Staff will take action if it's needed, but we ask you to refrain from poking them about it every 5 minutes.
This happens when all of the bots from the banking which you are attempting to use are full, as we do not load the inventories of full bots in the general view. You will have to wait until they have more space in their inventory.