A tripwire hook is not connecting to the string when I put it by there unless its a three by 1 and the trip wire hook is showing

What I expected to happen was: I expected the hook to go down like it was connected to the string.

*What actually happened was: It stayed in the upright no string attached position

1. Put a trip wire hook down
2. make sure the area is over 3 by 1
3. place string by the hook