could't set LNB with only one LO of 10750 MHz with Diseq switch settings

[levgenv]

I could't set LNB with only one LO of 10750 MHz with Diseq with two Switch Inputs. i set Lof High (MHz) to 0 press enter, set Lof Low (MHz) to 10750 press enter, set Lof Switch (MHz) to 0. and it immediately reset to universal lnb. i can set one lnb without diseq switch without any problem.