DataSource Controls :: Datareader - Loop Through Results In VB?

I would like to loop through my result set and generate a menu structure like this:

pagetitle
pagetitle
subtitle
subtitle
pagetitle
pagetitle

So far I have the following code but it doesn't generate the menu?

While reader.Read()
' set title
sitetitle = reader.Item("siteName")
mydata &= reader.Item("pagetitle")
' check subtitle exists, if so, build menu, loop though subtitles somehow?
if not IsDBNull(reader.Item("subtitle"))
mydata = "<ul>"
mydata &= "<li>" & reader.Item("subtitle") & "</li>"
mydata &= "</ul>"
end if
End while

Qeury and result set below:

sql:

SELECT subpages.subpageid, pages.pageid, sites.sitename, sites.siteid, pages.siteid,pages.pagetitle, subPages.subtitle FROM pages LEFT JOIN sites ON pages.siteid = sites.siteid LEFT JOIN subpages ON subpages.subpageid= pages.pageid WHERE sites.siteID = 1 ORDER BY sites.siteid, pages.pageid, subpages.subpageid ASC

results:

subpageid | pageid | siteid | siteid | pagetitle | subtitle
NULL 1 SCHS 1 1 Sandwell Community Healthcare Services NULL
NULL 2 SCHS 1 1 About Us NULL
NULL 3 SCHS 1 1 Your Services NULL
4 4 SCHS 1 1 Equality and Diversity Team at SCHS 1111
4 4 SCHS 1 1 Equality and Diversity Team at SCHS 2222
4 4 SCHS 1 1 Equality and Diversity Team at SCHS 333
4 4 SCHS 1 1 Equality and Diversity Team at SCHS 44444
NULL 5 SCHS 1 1 Single Equality Scheme NULL
NULL 6 SCHS 1 1 Diversity Strands NULL
NULL 7 SCHS 1 1 Equality Impact Assessments NULL
NULL 8 SCHS 1 1 Quality and Safety Committee NULL
NULL 9 SCHS 1 1 Contact Us NULL