[kh99]

OK, I ran a test and it seems to work. Are you saying that the exact code works with 10 or 2 but not 4 or 7 (I guess I'm saying, are you sure there's not a typo)? If you do this (add the 1|| in the condition):

<if condtion="1||TIMENOW%4==0">
Ad code
</if>

then it should show every time and you can make sure there's not something else wrong.

The only other thing I can think of is that it's not exactly random because it's based on the time, so if for example you have it set to 4 and you constantly hit reload, and the page happens to take about 4 seconds to load each time, you may end up with something that looks like it's not a 1 in 4 chance.