Promo code against order total

Hello

i have the following requirement :

get a 10 % discount on the order total

if you buy eg more then 100 dollar,

and if you mention the promo code XXX0001.

this does not seem to work for ask for modifiers,

- > as if I qualify them against order total

the discount does not get applied ..even if I select the promo code via the promotions (actions promotions on the order heaeder)

any hints on how to solve this ?

thanks!

Els