Hello there, I recently purchased an RB67 Pro-SD with a KL 90mm f/3.5L lens. I am having problems getting the mirror lockup function to work. The KL 90mm has no knob for mirror lockup, just the socket for inserting the cable release. As I understand it, the procedure is to screw a cable release into the socket, which should cause it to elevate so that you can see the red line appear. Then you can depress the camera's shutter button to fire the mirror, and use the cable release to fire the lens shutter. So far so good. The problem is that when I screw a cable release (I have tried about 5 different cable releases) into the socket, it does not cause the socket to elevate sufficiently to put the lens in mirror lockup mode. If I screw a cable release in and then pull on it I can bring the socket out far enough to see the red line and this successfully engages mirror lockup as long as I keep the socket pulled out, but of course this is useless. So I am wondering if there is a special cable release for the RB67 which causes the socket to elevate more than normal? Or if not has anyone else experienced this problem and resolved it somehow? Thanks in advance!