How can you tell if a DVD+RW is finalized or not?

I burned movies with Nero onto two different brands of DVD+RW (Phillips and Verbatim). The Verbatim plays back on my Apex and my friend's system. The Phillips only plays on my Apex. I know some DVD stand alones can read - but not + or R but not RW, but these are both +RW DVDs. Why won't they both play? I got to thinking maybe one was finalized and one wasn't? Apex plays just about anything. Nero appears to autofinalize (the finalize box is checked and greyed out so you can't choose not to finalize). Am I doing something wrong?