Gallery with identical lines

Hi,
I’m getting stupied with the galleries. I have pictures in same heigth 600 px and different with f.e. 153, 190, 120 etc.
How can I create a gallery (without inserting every image in a seperate box) that every image is on one line in the bottom?
http://pfab.wom.server49.vorschauseite.eu/haustuere-holz-classic/
Everything I’m doing doesn’t work escept putting every image in a own box.

I also just installed http://bdwm.be/rgg/demo/ but this doesn’t seem to work with the theme.
I get only the error that gallery short code can’t be fond.
http://pfab.wom.server49.vorschauseite.eu/gallerie-test/

For your support thousand thanks in advance.

Greetings
Michael