I' m feeling a little on the slow side here[&:], but can
someone please tell me how to keep my safety line
from sliding down the tree?

I know I' m supposed to run the knot end (including
the prusic hitch) through the loop end...I' ve been
able to follow the directions that far....but,
the safety line/rope just slides down the tree[:@].

Can someone give me a little direction here?

Thanks
TB