Air Application URL Path Issue

I am trying to invoke a  content of the file which is in shared folder from Air application.
Version : Flash builder 4.5,Flex3.6 sdk and Air 2.7.

for this am using the below code..

var request:URLRequest = new URLRequest();
//request.url = ('file:///c:/params.txt'); - This is working fine
request.url = ('file:///172.20.188.25/Share/chk/Property/params.txt');  // its not working
trace("Unable to load URL: " + request);
var variables:URLLoader = new URLLoader();
variables.dataFormat = URLLoaderDataFormat.VARIABLES;
variables.addEventListener(Event.COMPLETE, completeHandler);
try
{
variables.load(request);
}

The same part of code ,I tried in Flex application is working .but in Air application its not working.
Its urgent requirement,If any one know the way to resolve this path issues.
Kindly let us know.
Thanks in Advance !!