update...
...my 3rd roll was not success loaded. The rewinder (with 2 red dots) didn't rotate, I kept trying advance 6-7 times, still won't. So, I rewind back, totally waste films. Can I save those 3 rolls??? How to pull back the leader after I rewind all back???
thanks everyone for all the advises. the 4th roll loaded successfully (well, I haven't finished the whole roll yet, but, I saw the rotation while I advance.) I used the one I trim the leader. I haven't tried one without trim.
another thing I felt so stupid thinking back...I followed the diagram, the diagram show the film leader, and the leader show trim straight...guess what, I trim all rolls striaght!!! not until I saw all your advise, post, and links, I found out, it is not trim straight...so, I end up need to re cut the shape back...
well, always have the first time embreassment...I guess I will always remember this and have a good laugh about this later when I am good on every loading film to Leica....
thanks so much for all your encouragement...