How do i??

how do i like when i select something in a combobox it will trigger some visibility function?

like i have this comboBox with item F and M
when i click on the comboBox i selected F

then my label.visible = true and txt.visible = true

i trying it on when comboBox_change()
but it won't work

it goes in the Combo1_Click() event. Change only occurs when a user types in the box.