[OTP] VBA Using combobox in Excel

I managed to follow almost every step you mentioned, however i've got the following error message when running the code.

Run-time error '438':
Object doesn't support this property or method

with the following line highlighted in yellow:
thisRow = Worksheets("main").ComboBox1.ListIndex         ' Country list must start at row 1 for this to work

Any idea what's wrong?

gidyeo