vbscript error

Hi,

Microsoft VBScript runtime error '800a000d'

Type mismatch: 'Session(...).RequestMap'

/yeomanlocal/GisDispatcher.asp, line 8

The above error, I am not sure what error '800a000d' .

This is the data I am trying to call.

<SCRIPT LANGUAGE="VBScript" RUNAT="Server">

Const SESN_GIS = "GIS_SESSION"


Function GISDispatcher_RequestMap(ByVal TheId,ByVal topleftX,ByVal topleftY,ByVal brightx,ByVal brighty,ByVal msh,ByVal msw)
'On Error Resume Next
GISDispatcher_RequestMap=Session(SESN_GIS).RequestMap(TheId,topleftX,topleftY,brightx,brighty,msh,ms w)
End Function


Function GISDispatcher_RequestVectorMap(ByVal TheId,ByVal topleftX,ByVal topleftY,ByVal brightx,ByVal brighty)
'On Error Resume Next
GISDispatcher_RequestVectorMap=Session(SESN_GIS).RequestVectorMap(TheId,topleftX,topleftY,brightx,br ighty)
End Function


</SCRIPT>


This is the code I am using from the asp.

response.redirect ("bmpcon2.asp?userid=1&topleftx=&Lon1&&toplefty=&Lat1&&brightx=&Lon2&&brighty=&Lat2&")



I am not sure what is causing the problem.

Also are there any good vbscript or asp resource sites on the Net.