dblookuplistbox dropdown list problem

[ssfftt]

i have a dblookuplistbox contains list of names (at least more than 1) that can be selected.

everytime i run the application, the first time i click on the dblookuplistbox, the dropdown list appears, but only one record (one row) is visiable, to see other s i have to click on the arrow on the right hand side.

and if i click on the dblookuplistbox again (second time onwards), the list will appear as its default settings (normally 7 or 8).

why doesnt it appear as default setting on the first-time click?

how can i fix it?