Networks days between different tasks/Filters

Thanks For your help team.
I got there in the end with this solution - 
1. 

Decision stage = SUMX(

    FILTER(

        'infodbo Application_Tasks',

        'infodbo Application_Tasks'[Task_Code] = "DAPDEC"

    ),

    NETWORKDAYS(

        'infodbo Application_Tasks'[Initiated Date],

        'infodbo Application_Tasks'[Complete Date],

        DAY

        7

    )

)

Pre-assessment time = SUMX(

    FILTER(

        'infodbo Application_Tasks',

        'infodbo Application_Tasks'[Task_Code] = "DAPPREASS"

    ),

    NETWORKDAYS(

        'infodbo Application_Tasks'[Initiated Date],

        'infodbo Application_Tasks'[Complete Date],

        DAY

        7

    )

)  
PMD to Decision date = 'Measures table' [Pre-assessment time] + 'Measures table' [Decision stage]
Giving me the total work days from Pre-assessment task start to Decision stage finish.
Tim H