PCS7 V6.2 SP2 ,HOW TO ENABLE DEFAULT MASTER CHECK BOX

Dear experts,
Iam using pcs7 v6.2,sp2,In this we are using server client concept.One ES/OS,redundant server,three OS.Iam downloading all the program from Es/Os only.ButES/Os wincc is not communicating and then all theOS fetch data's from secondary server only not from primary.For that we find problem during configuration time ,default check box in wincc redundancy menu is not enable.I tried to enable it but it won't .I expect your valuable answers soon for both problem.