Why do I get 800A138F errors?

Microsoft JScript runtime error '800a138f'   '<variable>' is not an object    Microsoft JScript runtime error '800a138f'  Object expected    Microsoft JScript runtime error '800a138f'  '<variable>' is null or not an object    Microsoft JScript runtime (0x800A138F)  '<variable>' is null or not an object

 
For starters, of course, make sure you are referring to an object that exists. If you are trying to access the Application object, for example, and you spell it wrong, you're going to be out of luck. Make sure any custom functions you are calling are in the script, or that the include file they're in is actually being included. 
 
When using both languages in an ASP page, you can get this error if you try, from server-side JScript, to call a client-side VBScript sub or function. See Article #2045 for details on mixing server-side scripting languages, because in certain scenarios, your function call in one language will occur before the function even exists in the other language. 
 
Do not use CreateObject by itself in JScript. Use the following syntax: 
 

<script language=javascript runat=server>      var obj = new ActiveXObject("Prog.Id");  </script>

 
Don't worry, this has nothing to do with ActiveX objects on the client.