Amadis

Hi, I'm using the X-T2 for a while and recently did some tests with long exposure. I switched to the Mechanical Shutter and set the dial to "B". But somehow it doesn't work. When I press and hold the shutter release (or block it when using the cable release) it sets the exposure to 30 seconds and stops after that period of time. Is there any additional setting I need for the Bulb Mode? Thanks a lot!