Yeah rememebr the 20-25 are more sensitive than the 10 silly!!!
Actually the 10 are more sensitive. They measure 10mIU in your urine, it has to get up to 20mIU to be positive on the 20 ones.
So Ren I would say you have around 10mIU hcg but not high enough to register on the 20mIU one yet so it might just take another couple of days, don't stress!!