How to Erase a cdrw wrongly burned

[guguf]

I tried to make a backup of a cd I own protected with securom new on a cdrw using a Waitec Aladar burner.
The disk is not readable by either the player and the burner.
I tried to erase it but no way.
Clone or nero tell me that the cd is erased, but it's false. The cdrw is still unusable.
Does anybody knows how to erase it?