Awe, Peter, I am so sorry you did not get an expected result : (. I hope somebody who had the same surgery and has experience with it will jump in this thread soon and have some answers. Is that device adjustable at all after it is put in place ? Since you stated that it needs just one pump and most need 2 or 3 it does suggest much faster opening and thus perhaps means (as you suspect) that valve is not tight enough.
Will you have follow-up with your surgeon soon ? Does he have any idea why is it happening and can it be adjusted to be perfect ? Can urge part be controlled with meds that somewhat relax bladder ?