Fetch from same form, Update two records from same form

Fetch from same form, Update two records from same form

I am having a problem updating two separate records as a result of a change in my incident report form.
 
When you select the equipment that has faulted, and has been replaced, the faulted equipments status changes to "Faulty", and what I want, is when you select the replacement equipment, that it's status changes from "Backup" to "Active". Unfortunately if I put the bold code in below, I get a 'null' response on update.


if((input.Condition == "Faulty & replaced with spare"))
{
     EquipmentStatus = Equipment_List[Equipment ==   input.Equipment_List1];
EquipmentRepairStatus = Equipment_List[Equipment == input.Replacement_Equipment];
     EquipmentStatus.Status="Faulty";
EquipmentRepairStatus.Status="Active";
}