HELLO ZAKARYA..
As far as setting parameters of multiplexer are concerned i will suggest you to increase the bandwidth from 10 GHz which is a default value to 20 or more for obtaining good results..i have noticed the same when i increased the bandwidth..
Now as far as filter order is concerned, higher the order more smooth is the response..so i ll suggest you to keep order 4 or more..it also depends on the application as well..
about the depth i will also like to know it..
Thanks & regards