> what would be the reason behind it and in what way i should proceed?
You have custom code and we don't know what you have changed.
If you need further help then you need to create a [url http://homepage1.nifty.com/algafield/sscce.html]Short, Self Contained, Compilable and Executable, Example Program[/url] (SSCCE) that demonstrates the incorrect behaviour, because I can't guess exactly what you are doing based on the information provided.
Don't forget to use the [url http://forum.java.sun.com/help.jspa?sec=formatting]Code Formatting Tags[/url] so the posted code retains its original formatting.
I have the table names which has prefixes and post fixes as html tags to get the right formatting in the table header.
i.e <html>Example One</html>
these names i am taking and inserting in the list.
i think because of that when i go through the list items with the up and down buttons the previouslt selected element goes blank , i mean it becomes same as background color(white). so cant able to see that.
How to overcome this problem?