setting the visibility of server controls

[ac26]

Hi,
I am using code as follows:
ddNewProperty.Attributes["onfocus"]="document.getElementById('" + lblSelectedProperty.ClientID + "').style.visibility =hidden; ";
to seet the visibilit of the above and different server controls such as textboxes and dropdownlists on my webform, but to no avail. Can someone please point out the mistake in my code?
Thanks in advance

[TheNige]

In vb.net we'd use

ddNewProperty.Attributes.add("OnFocus", "document.getElementById('" & lblSelectedProperty.ClientID & "').style.visibility=hidden;")