Disable a filter while tables are related

Hi, 

I have some tables 2 fact tables: one from timesheet for hours used, the other one from SQL to get the count of tasks. 

the usernames and report names are different in the 2 platforms.

I am able to build a measure like: 

AverageTimeUsed = Divide( sum(timesheet[hours]), sum(SQL[CountofTasks])) to get the average processing time for each task. 

And I d like to have another measure shows the team average processing time. 

In a page I will have a table compares the processing time and average processing time, and add 2 slicers on username and date. 

when all the team members are  selected the 2 average time should be the same; and when some team members are selected, show the comparision between these people and the team average(it should not be changed by the username filter, but should be changed according to the date slicer) 

I tried

calculate(sum(timesheet[hours]),

ALL( timesheet[username]))  and

calculate ( sum(timesheet[hours]),

removefilters(timesheet[username]))

both are not working. 

And i tried to put all the columns related: 

calculate( sum(timesheet[hours]),

removefilters(timesheet[username]),

removefilters(sql[username]),

removefilters(usernameMappingTable[username])) 

or use ALL instead of the Removefilters function, the data are still changing with the slicer. 

Thank you for reading and all suggetions are appreciated!