Conditinal Formatting

[HESH]

Hello
How do I make a cell flash when its value is less than zero

 

[HESH]

I tried the following method
in conditional formating the rules is
=and(A1<0,mood(second(now(),2)=1)
vba code is
Sub Falshing()
dim mytime as date
mytime = now() + timeserial(0,0,1)
Application.OnTime mytime,"CalculateIt"
end sub

Sub CalculateIt()
Application.calculate
End Sub


Where is my fault