Thank you for your answer. No, I think I found out what is wrong. The preset I use has a wah pedal block (Chrome) which is assigned to expression pedal 1. If I change the wah pedal type to eg. the UK Wah 846, the pedals get mixed up and the wah pedal is now assigned to expression pedal 2 which is now partly a volume pedal and wah pedal. The wah sound is there but expression pedal 2 also controls the volume block. In other words, it's kinda half-half-situation. Expression pedal 1 is now the normal sound without wah. However, the the pedal doesn't work on expression 1.
