Block module visibility settings are bypassed.

Helo,

I've create a custom block with contain simple html link to other page, I set visibility for anonymous users only. But after I login, the insert_block filter still render the block and visible to authenticated user. I try to set PHP block visibility with use !$user->uid as return TRUE value and set permission to anonym to use PHP block visibility permission, but with no luck, the block still rendered when i login. But when the block I try to put on left sidebar, it's working normaly.

Any advice? I'm just web designer with no experiences with module development.

Thank you.