It will fit.
To put it in...put the top tip under the holder then slide it backwards until the handle is in the rear holder then position it so the front of the handle will fit behind the stop and rotate it down into the locked position. Now the head has to be in the correct position on the handle to make it all fit. I had to play with mine for a while the first time to get it to go, but it will go when the head is in the correct position on the handle.
Steve