Fijate en:
http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=40131&lngWId=1
http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=11020&lngWId=1
http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=29615&lngWId=1
http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=38614&lngWId=1
http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=12364&lngWId=1
que tienes ejemplos.