First locate a crimp on the marks where the tool needs to align. Clamping the tool with 3 clamps goes like this. First clamp is away at the pivot point, second clamp is side to side, thrid clamp is doing most of the pressing work.
Image 2) This is what happens if you don't pre crimp and give the tool a positive location before clamping. The line should be centered in the groove. The next one was.