Please Help me out with This

I Have Created A Combox in UserForm , which should show the "Accounts" in the Dropdown.
And when i Select Particular Account ...example "1" ,it should populate steps under it like X.Y.Z in ListBox

Have used "ComboBox1.List = ThisWorkbook.Worksheets("Sheet3").Range("A1:A26").Value" to Display content under A
which doesnt shows.. until i type something in Combox..!!!

------------------
On Sheet
------------------
A B
Accounts 1
1 X
2 y
3 Z