Tempo changes have no effect

When I change the tempo in the Transport Bar (F2), the tempo of the playback doesn’t change. The tempo track is deactivated and even empty. Any advice?

Sorry, in a 4/4 time signature I accidentally spread a drumbeat pattern over 4 bars in stead of 4 beats. Cubase probably hit its fastest limit …

btw, the “speed” of Cubase is unlimited. If 300 bpm isn’t fast enough, use a time sig like: 4/16, or 4/32.