Divide / Calculate / Countrows with filters

Hey Gurus,

I'm looking for help creating a measure that can calculate a percentage.

I have tried multiple way's of getting this to work and I'm also willing to split them into different measures if that is the only way to do it.

TotalLSC = 
CALCULATE (
    DIVIDE (
        COUNTROWS ( FILTER ( 'data cfb', 'data cfb'[COM_DeliveryPMA] = 1 
            && LEFT('data cfb'[Node Code], 3) = "LSC" )),

        COUNTROWS ( FILTER ( 'data cfb', 'data cfb'[COM_DeliveryPMA] = 1 )
)))

I want to divide total rows where DeliveryPMA = 1 and Node Code starts with LSC divided by the total rows where DeliveryPMA = 1.

Thanks in advance, I really appreciate your help!

/B