show hidden Button when fields are used

I’m try to create a send button that is hidden or inactive until several field values are filled.

two of them are time stamps 1st "sendtovedor"

                                              2nd "Submitdate"

and the 3rd is a $ value title "private.totalcost"

and Button Name is "Button0.3"

I looked through and found a few similar scripts but and I tried to modify them to work for my purpose but neither worked. I don't what I'm doing wrong. please help

I want all three fields to be filled before Button is displayed and or active.

Thanks,