Report Function and calculation

I use Report Builder for summary at group footer.

I tried to function builder like

Sum(Query.MyField), but the report builder does not like this for some reason.

I tried to use Query.MyField, Report Builder still does not like it to give me ColdFusion does not recognize it.

I need to have calculation field like

sum(MyField1 * MyField2)/ sum(MyField2) and sum(MyField2) base on group elements.

for my summary field and need change color if it is neccessary.

Does Report Builder support client side code like Javascript to change client side behavior?

Your help and information is great appreciated,

Regards,

Iccsi,