This validation message comes from Format Control of form: patcotask. But it contains one bad validation:
In the default format control of patcotask, the second validation is: basis.time in $file<'01/01/50 07:00:00'
It is wrong validation because the current time alway greater than '01/01/50 07:00:00' , so the validation always appears and cannot pass. So to make it right and by pass the validation, should change it to:
basis.time in $file>'01/01/50 07:00:00'
After changed it, save the record and run again, now the Schedule Maintenance task record is saved succesfully.