Clamp on Airflow Meter Boot?

[Mystert]

I just changed out the injectors, vacuum system, vacuum hoses at the throttle body, and airflow meter boot on my M117 560SL. I cant figure out how the air flowmeter boot to throttle body clamp works. I put the tang in the slot and twisted the bolt, it tightened a little then it just slipped and started to move around the throttle body until it jammed up in the throttle linkage. Can someone explain how this works please? Thanks