Custom height/width for thickbox in WP Backend-Collection of common programming errors

I use thickbox in the WP backend for preview or other content. On own pages in the backend works my script very fine and a can use custom width and height for the thickbox. below my code:

Now to my problem and question. I will use a thickbox on the page wp-admin/plugins.php and here dont work the script. WP set the height and width always to the core-values and this is to small for my request.

Maybe other readers have an idea or a solution.

Many thanks!