Problems with combo box

[lakefx]

I am actually updating an access 97 quick database for bookkeeping. I added a new table called subtopic. I have made a relationship to the book table(subtopicid-subtopicid) and even added dblclick to the event thingy(lack of better terms). I added the combo box to the form and am able to pull a drop down window, however the doubleclick will not pull up the subtopic form in order to add another entry. What am I doing wrong? Please help me...