setting the width of a panel programmatically

this is a stumper for me
ive got a panel width that im trying to set programmatically
if i set it with an integer it works great
but if i set it with the width of an image (which is an integer) - it tanks
ie,
 
Dim imgB As Bitmap = New Bitmap(Server.MapPath("" & url))

u = imgB.Width

toolbarP.Width = 600 'this works
galleryP.Width = u 'this does not !!!!???!! 
someone out there answer this for me?
 
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