Temporary (Placeholder) Text in Form Field but for Numbers only

Enter the following scripts:

Custom Format:

AFNumber_Format(2,0,0,0,"",true);
if (!event.value)
{event.value = "Enter message here";}

Custom Keystroke:

AFNumber_Keystroke(2,0,0,0,"",true);

Custom Calculation:

if(!event.value)
{event.target.display = display.noPrint;}
else
{event.target.display = display.visible;}

Your script has curly quotes and a curly quote in front of display.visible.  Make sure you use a plain text editor like Notepad to write your scripts.