Panel not maintaining scroll position

I am new to ASP .NET. In my webpage there is a panel with vertical scroll
bar enabled.Inside the panel there is a treeview control.I'm populating its
nodes at run time through database connection.The nodes are
large in number, sothat I've to scroll down to view the last nodes. The
problem is that when I scroll down to see the bottom most nodes,the scroll
bar goes back to the initial position.ie,I'm able to view only the first few
nodes.I cant view the last nodes not more than one second!!!
Hope U'll 've the solution and THANK YOU VERY MUCH! in advance...