Optimal task time scheduling and assigment problem - Excel Solver

I'm trying to resolve an assigment problem using Excel solver.

I have a number of task that each takes a number of days to complete.
I have a number of person to do the tasks. Each takes the same amount of time to resolve the tasks.

There are the following constraints:
- each task has to have 2 persons assignet to it
- each person has to be assigned a total time of 40 days

In theory the solution is something like this:
- Persons 1 and 2 to work on Tasks 1 and 3
- Persons 3 and 4 to work on Tasks 2 and 4
- Persons 5 and 6 to work on Task 5

I want to add an extra constraint regarding the Persons and how to assign them together. There are 3 types of Persons: Leader, member and newbie. The constraints would be:
- two Leaders cannot work on the same task
- two newbies cannot work on the same task.
All other combinations are possible: Leader and member, Leader and newbie, member and member, member and newbie.

Extra: for the Time Assigned range is there a better way to write the sum function?

This part is already solved, please take a look at post #6. I'm looking for a solution to optimal schedule the tasks as the first step before the people assigment.