StreamReader problem

[zhujp98]

I have .net 2003
in my code
if I use
StreamReader dataInput =new StreamReader(c0Name), I will get error

Type or namespace streamreader could not be found

if i use
System.IO.StreamReader dataInput =new System.IO.StreamReader(c0Name)

It works,
I remember, i my previous project i do need to include the System.IO in my code.

THX