Very similiar question asked and answered a few days ago:

You can't just select the name. You have to select the name then exit
the field with a macro set to run on exit from that field. Something
like:

Sub Fillin()
Dim oDoc As Document
Set oDoc =3D ActiveDocument
Select Case oDoc.FormFields("DropDown1").R=ADesult
Case Is =3D "Sheila"
oDoc.FormFields("Text1").Resul=ADt =3D "321-1234"
oDoc.FormFields("Text2").Resul=ADt =3D "
Case Is =3D "Greg"
oDoc.FormFields("Text1").Resul=ADt =3D "987-6754"
oDoc.FormFields("Text2").Resul=ADt =3D "
Case Else
oDoc.FormFields("Text1").Resul=ADt =3D "???-????"
oDoc.FormFields("Text2").Resul=ADt =3D "
End Select=20
End Sub