I try to customize my block id and it doesn't work I create a block which I want to theme.

My block ID is 1.

In my mind it was simple as create a file block--block--1.tpl.php and make some theming on it, but I didn't see any of my change.

One important point here, is that I'm using Panel.
I wanted to drop this block into a panel region.

this is what I see in firebug

contextual-links-region panel-pane pane-block pane-block-1


Thanks a lot.
You can set your block to a 'system block' from within the Panels pane management interface. It should then pick up on the system level block template files.

This also may be a duplicate of How to use a custom block template when the block is embedded in a panel pane?, but there wasn't a definite 'good' answer there either it seems.