type mismatch on code that was not chnaged?

type mismatch on code that was not chnaged?

I have this error showing when I click on save:
" Mismatch data type for function 'getAge' at argument index 1 expected data type TIMESTAMP found data type BIGINT"
it occurs in the line beginning row.age:

    if ((row.personId.dateOfBirth  !=  null)  &&  (input.dateAndTime  !=  null))
    {
        row.age = thisapp.stc.getAge(row.personId.dateOfBirth, input.dateAndTime);
    }

this is code that was not changed but with this error I cannot make edits any way.