After trying a little bit. I aswer by my self :-)
This line works in my AssetsIB.csv
DAX,13000,0.5,0,0,0.5,0.5,320,0,-1,1,DAX-FUT-20230915-FDAX-EUREX-EUR,0,Dax Microdaxfuture FDXS

Looks like that the Multiplier makes the magic: FDXS --> -1, FDXM --> -5
mabe this helps anybody