run a model from python problem

I am using arcGIS 10.0 SP5

I have the following code :

import arcpy

arcpy.ImportToolbox(r"C:\Documents and Settings\Derek\FRAME\FORTEST.tbx", "Derek")

arcpy.TEST_Derek()

The model is names TEST
The toolbox alias is Derek

When I try and run this I get an error

AttributeError: 'module' object has no attribute 'TEST_Derek"

What I want to do is to run the model TEST from the toolbox FORTEST

I have tried the same code using arcGIS 10.1 and it runs perfectly. is there something different in arcGIS10.0 and is there a workaround?

Any help would be appreciated

Thanks

Derek