Rest call with basic Auth give me an error 500

Hello, 

I need to call an external rest service from a SBM modscript (which is called by a notifiication).

I create a rest data source with the basic auth.

I create a script but the response is an error 500.

I try to call the URL of the endpoint with SOAPUI on SBM server and it's OK.

I added the authentification in the "Headers vector" but the result is the same with or without the authent in the header.

Can you help me to figure out this case ?

Here is the script : 

var issueID = Variant();

var itemMaint = Ext.CreateAppRecord(Ext.TableId("UMA_MAINTENANCE"));
itemMaint.Read(Shell.ItemId());

issueID = itemMaint.GetFieldValueString("TS_ISSUEID");
 

//Ext.LogInfoMsg("Cindy test modscript maint : issueID =" + issueID );

var restSource = Ext.CreateAppRecord(Ext.TableId("TS_RESTDATASOURCE"));
restSource.ReadByColumn("NAME","Update");

var result = "";

if ( !restSource.Post( result,"",[Pair("ticketId", issueID)],[],[Pair("Authorization","Basic xxx")]  ) ) {
    // write an error to Event Viewer
    Ext.LogErrorMsg("IA - Rest call failed in script " + __FILE__ +   ":\n" + Shell.GetLastErrorMessage() );

}
else {
         Ext.LogInfoMsg("IA - Return rest call update  : " + result);
}
     

And here is the error on the event viewer : 

RESTDataSource::CallRest
URL: https://xxx/sbmproxy/xhp?url=httpsxxx
Return: false
ResultDataSize: 100
TimeoutVal: 30

ErrorMessages: HTTP Response Code: 500