You may need to add an authorization header to your stHttpHeader table.
See Base64 encoding/decoding sample code for a subroutine to perform the needed base64 encoding.
Here is an example from one of my projects:
sLogBuildString = sLogUser + ":" + sLogPassword;
Base64EncodeDecode(sLogBuildString, sLogBuildString, 1, nJunkStatus );
stHttpRequestHeaderLog[0] = "Host: " + sHttpHostNameLog;
stHttpRequestHeaderLog[1] = "User-Agent: Opto22 PAC";
stHttpRequestHeaderLog[2] = "Authorization: Basic " + sLogBuildString;
stHttpRequestHeaderLog[3] = "Cache-Control: no-cache";