Combo box with dynamic list driving text box entry on a userform

I have a userform with a combo box and a text box. I want the combo box to populate from Sheet 1's inputs and drive the input in the corresponding text box. I have tried:

...
.Combobox1.Value = ws.Cells(.providerNum.ListIndex + 5, 4)
.Texbox1.Value = Application.VLookup(Me.combobox1.Value, Sheets("Sheet2").Range("J1:K1000"), 2, 0)
...

with no luck...