erasing RW Dvd discs

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I am an elderly man and having problems erasing RW disc to re burn.
I presume I should be using Disk Utility which I do I click on complete erase and wait and when its finished i try using it to no avail.

I am using toast 9 for burning i drag item to be burnt into the appropriate section and click on button, request comes up to insert blank disc and after hearing a few noises with the drive it then ejects can anyone help this old man please my email is (e-mail address removed)