yes I've done it and install the DLC after.
But I've found what i did wrong and it works now.
Contrerely to the other DLC I had to chose cyrenaica and enter the serial N°
Before I only had to introduce the serial N°

I have installed Frontlines Cyrenaica and when i try to start it, i'm transfered to the slitherine site PzCo 2 Cyrenaica in place of start the game I've tried to start another campaign but when I click on it, nothing happend ===> panzercorps 2 doesn't work anymore since the latest update and install...