WCAT & TinyGet testing using HttpHandlers

I've searched on Google for an answer to this but there doesn't seem to be much information out there. Does anyone know if you can use WCAT and or TinyGet to test an asp.net application that uses 开发者_运维知识库HttpHandlers? I've tried both of these tools and I'm getting an Internal Server Error 500. Looks like a problem with the HttpContext?

[NullReferenceException: Object reference not set to an instance of an object.]
   BCT.BaseHttpHandler.Process(HttpContextBase context) +622
   BCT.UADTimeHttpHandler.Process(HttpContextBase context) +55
   BCT.BaseHttpHandler.ProcessRequest(HttpContext context) +75
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep
.Execute() +181
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& comp
letedSynchronously) +75

I've also tried using the WCAT Fiddler plugin but that has a different error about a possible missing reg key.

Definitely you can. WCAT just makes HTTP requests, exactly like any browser. You've got a bug in your handler, is all. What does the code that the stack trace points to say, here:

BCT.BaseHttpHandler.Process(HttpContextBase context) +622 

?