Combo Box visible when it should be hidden

Hello Everyone...

I really hope you could help me with this.

I face a problem with combo box, which is that combo box always appear (refer attachment file).
I didn't know why this happen. For the other combo box run as usual compare to this combo box.
Is it related to function or coding or both of them?

I hope all the member of this forum understand what I face and can help me out this things.

Thank you for all your help.