NullReferenceException

The control is good.
But when i used authentication, this is the error that gets thrown:

 Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
   b.a() +32
   GleamTech.Web.FileTransfer.UploadHttpModule.c(Object A_0, EventArgs A_1) +1190
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +92
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +64

Any ideas what Im doing wrong?

and here is the web.config

<?xml version="1.0"?>

<configuration>
  
    <appSettings/>
    <connectionStrings/>
  
    <system.web>
      <pages>
        <controls>
          <add tagPrefix="GleamTech" tagName="FileVistaControl" src="~/FileVistaControl/filevista.ascx" />
          <add tagPrefix="GleamTech" assembly="GleamTech.Web.Controls.FileVistaControl" namespace="GleamTech.Web.Controls" />
        </controls>
      </pages>

      <httpModules>
        <add name="UploadHttpModule" type="GleamTech.Web.FileTransfer.UploadHttpModule, GleamTech.Web.FileTransfer" />
      </httpModules>

      <httpRuntime maxRequestLength="2097151" executionTimeout="7200" />

      <webServices>
        <protocols>
          <add name="HttpGet"/>
          <add name="HttpPost"/>
        </protocols>
      </webServices>
      <!-- 
            Set compilation debug="true" to insert debugging 
            symbols into the compiled page. Because this 
            affects performance, set this value to true only 
            during development.
        -->
        <compilation debug="true" />
      <authentication mode="Forms" >
        <forms name="mockups" loginUrl="login.aspx" protection="All" timeout="20" />
      </authentication>
      <authorization>
        <deny users="?" />
      </authorization>        

    </system.web>
</configuration>

The web.config seems correct, I have sent you an updated version of the upload DLL. It may fix the problem or at least you will see the actual function names in Stack Trace of the error message. Please send me the error message again.

Let me know.