Access is Denied Error when customise MSCRM for a validation by other asp.net application

Question

Access is Denied error when customize MSCRM by gettng a value from other asp.net application when both are in same virtual diretory path.
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I do customize MSCRM, where the validation is to fetch a value from table I use the below code written in _javascript

var oXmlACDoc = new ActiveXObject("Microsoft.XMLDOM");
oXmlACDoc.async = false;
oXmlACDoc.load("http://octopus/crmcustom2/checkbrndata.aspx?accountname=" + sAC);
// Load the result node
var oNode = oXmlACDoc.selectSingleNode("duplicatesFound");
 
as per the path given I have deployed a .net application which return me the value as xml node that I receive inside crm form validation, ie

var oNode = oXmlACDoc.selectSingleNode("duplicatesFound");

my .Net application is crmcustom2 as per the path above.
Octopus is the directory(D://program files/MSCRM) where MSCRM and my crmcutom2 applications are deployed in IIS.(so normally users login to MS CRM in the browser by just type http://octopus)

The above code is working fine in test server MSCRM application with the path localhost instead of octopus(which is a server path).
But in server if I pass a value in the path http://octopus/crmcustom2/checkbrndata.aspx?accountname=" + sAC , I get the Access is Denied error in CRM.application (but when I test the result for the above path by passing a sample value from the browser like http://octopus/crmcustom2/checkbrndata.aspx?accountname=cctv-vcr, then I get a result. ).
I suspect it’s a user permission issue , if so whats the things need to be taken care?/ please suggest.