I should further point out that after I created my new role mytestbkadmin I tried two things: 1) I tried clicking the add role to this block (or whatever it says) button on the block and added a user. She tested true but so did someone I didn't add. and 2) I tried adding a user to the role with system context. Again the user tested true but so did someone I didn't add that way. And neither one could see the block.
Again thanks