When using this style of bobbin holder and you are unable to pull thread out of the tube, you will have to adjust the tension by simply spreading apart the arms that hold the thread spool. Don't spread the the arms too far or the spool will spin freely. Just find the right tension for your tying style. Bend the arms until you get it just right.
The bobbin holders shown below have other methods of adjusting the tension on the thread spool.