Embroidery. The bobbin thread comes through to the top so that I have white areas in my monograms.

Question

The bobbin thread comes through to the top so that I have white areas in my monograms. what is causing this and how can I stop it. Have used the button that is set on 2 for embroidery and lowered , I guess itis tension. This doesnt seem to help. I am sure I am loading my bobbin correctly. I am using isacord thread.Not sure what else I can do. Would appreciate any help.Thanks