findclientbyBL_ID(%sellerID).RPData.value["jobID"]
There's your problem. By the looks of it, you are storing all of the data you want to access on
the client object a script object. However when the client leaves, it is all deleted (im assuming).
If you're an inexperienced coder, I recommend you just give up on trying to do this now (not trying to sound negative, but its a fairly large task to fix this), or come back to this when you have a better understanding on scripting.
What you want to do is change everywhere how the script stores the data, and put it onto the brickgroup. You can get the brick group from various objects quite easily:
%brick.getGroup()
%client.brickGroup
%player.client.brickGroup