Populating a combo box

I’m using vb6 with an ADODC control.

When the following code is run it comes up with an error saying
Field ‘tblStock.Supplier’ cannot contain a zero length string.

With adoStock.Recordset
cboSupplier.Clear
While Not .EOF
cboSupplier.AddItem .Fields(“Supplier”)
.MoveNext
Wend
End With

It breaks on the .MoveNext line.
All I’m trying to do is put the results in a combo box.