‘Ok, You’ve deleted 0 messages’. is this a bug?

Hi, I'm having serious issues with the sweep and junk functions in my mail box. Until recently this has worked fine but i started receiving junk messages that i could not seem to block. When i select the message and sweep>delete all from>also block future messages i get the following message "Okay, you've deleted 0 messages from [junksender, normally something like =?UTF-7?B?K0FGOC1WYW5xdWlzQ3J] and added them to your blocked list". And it is obviously not blocking them. I thought that my blocked list was full as i've been adding to it for what seems like centuries so I cleared my blocked list and am trying to block recent junk. But this is not working  Can anyone help as I'm getting a ridiculous amount of junk mail and i'm tempted to stop using this account?