SecurityException when app moved to network

[pargat.singh]

Hi Everyone:
I have asimple app as below
using System;
using System.IO;
using System.Security;
class App{
public static void Main(string[] args){
StreamReader reader = new StreamReader(args[0]);
Console.WriteLine(reader.ReadToEnd());
}

}
I complie this app and call like C:\DSTest>DisplayFile
C:\DSTest\Test.txt and it wok fine.

When i move this app to network and call like
y:\DisplayFile C:\DSTest\Test.txt
i got an error but when i moved th file to same directory then it work
like
y:DSTest\\DisplayFile Y:\DSTest\Test.txt
Please help.Thanks in advance.
Parry