I can't negotiate when I play Prussia

[Ustaoset]

I am playing Prussia, but when I have finished a war with some of the other German states I can't find the "Open negotiation" bar in the diplomacy menu.
I know that negotiations don't work when I'm at war, but why won't it work when the war is over? This never happens when I play another country.

 

[OHgamer]

Do you have negative prestige. If so, you can not initiate diplomatic actions.

 

[Gen. Skobelev]

Negative prestige causes this.

oh well, no surprise OHgamer already answered this..

 

[Ustaoset]

Thanks. That was the problem.