ccalworkhours not giving correct result on Friday.

Hi Members,
I am trying to calculate the working hours between two different time using calworkhours function.
It is giving perfect result for all the days except on Fridays. I have check my calendar setting as well . Friday's setting is same as other working days.
I have pasted the Screenshot of Calendar and Expression along with it's result.

EscalationCalendar Image : 


Expression Rule and it's Result Image :  

I am expecting 6 hours but it's giving 2 hours and it is same for every Friday.

Please help on this ASAP.

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