copy Vhs tape to imovie

I know i asked this before but i’m hoping someone has the answer. I’m coping a vhs tape thru my Panasonic 100a camcorder and connected the firewire cable to my Macbook pro
I click on import form my Panasonic camcorder and i see the video in my capture screen. as soon as i hit capture a pop-up
drops down and says making a thumbnail and the video stops.
Why?
what am i doing wrong?
Thanks Peter
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Peter Lelievre