Not able to add % Mark column as filter in ThinkOrSwim scanner

Hi,
I am new to ThinkorSwim platform.
I am trying to add %Mark to pre market scanner as a filter but I couldn't find it available list. Does anybody know why it is not available?

When I created my own custom script with the below code, close in the below code is referring to the price after the market open not the premarket price of the equity. Does anybody know how to get it work?

def Val = ((close-close[Period="DAY"][1]/close[Period="DAY"][1])*100) >=5;
plot scan = Val;

I am not sure what I am missing. Appreciate your help. Thanks.

Thanks,
Sethu