How to assign output value of an activity in TFS build template

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TFS

coverage

We want to fail a build if its coverage is below 80%. To achieve this we have built one activity project which will calculate the % of code coverage and compare with our threshold value. Now i have modified my template xaml file to include my custom assembly as shown in this- http://stackoverflow.com/questions/14282652/fail-a-build-if-code-coverage-is-below-a-threshold-in-tfs2012 The problem is when i reference my assembly's output in xaml file, i get error which says activity cant be loaded in red. Can anyone help me to use my assembly's output in template's xaml file

P.S my custom assembly is not in same directory as the templates.