how to grey out/disible certain delete buttons in gridview

Hi, I have a template field with a delete button in  gridview . The delete button's command name is set to delete.
I want to, if in my sqldatasource.select the parentpageID property is NULL I want to disible/grey out the button...
something like:


Dim dv As DataView = TryCast(SqlDataSource1.[Select](DataSourceSelectArguments.Empty), DataView) 

while
dv.read

For Each item As gridviewitems
blah = ctype(findcontrol.gridview("deletebuttonID", linkbutton). linkbutton

dv("parentPageID")  = NULL
Then blah.navigateurl = ""
next
end while


Any suggestions particularly with access the gridview for this?
Thanks
Andy

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