VGA output on Lenovo Thinkpad X230 does not work

Hello Qubes community,

when i plug in the vga cabel to my Thinkpad, the cabel gets recognized and i can choose how to use the screen (Mirror screen etc.) but the second screen stays black. Also testet another monitor. Using Intel i7 processor.
If you need more information i can provide it, but i am new to the Qubes community and have not much experience.