title: does the oleobject in pb have defined the method open(ref string)?
body: <p>I got the error</p>
  
  <blockquote>
    <p>Error calling external object function open at line "hObj.Open(ref sOut)" </p>
  </blockquote>
  
  <p>when I run those code in PowerBuilder 11.5, here is the code:</p>
  
  <pre><code>string sOut
  
  hObj.Open(ref sOut)
  
  oleobject objXMLDOM
  objXMLDOM = GetXmlDom(sOut)
  
  Boolean bRet
  bRet = CheckOutputState(objXMLDOM)
  </code></pre>
  
  <p>This code is from a function. The param is (<code>ref oleobject hobj</code>)</p>
  
  <p>I have these questions:</p>
  
  <ol>
  <li>What's the use of string <code>sOut</code>? When i run this program, string <code>sOut</code> is null, and occurs an null reference error.</li>
  <li>Does the system defined the method <code>open(ref string)</code> already? But when I search the documentation of pb, I haven't find this method was defined, can any one give me some direction, thanks.</li>
  </ol>