Hi there! I have had repeated problems when I go to tie a knot to secure a rigging line taunt. My knots always end up with a gap between the knot and the surface that holds the line taunt. I’m sure this is a rookie mistake but it’s driving me crazy and taking away from the look of the model. What am I doing wrong? 
Thanks for any help you can give me.

Thanks for any help you can give me.