PowerPC MacBook Pro doesn't see HFS+ formatted external hard discs

I don't know if it's the proper place for my problem, but here it goes:

I just bought 2 WD external hard discs and formatted them (one of them in my Intel MacBook Pro and one of them in my friend's Intel Macbook pro). I can read and write the hard disc that my friend formatted without a problem, but the PowerPC Macbook pro cannot write either of them. What is the problem?

Thanks in advance...

There's no such thing as a "Power PC Mac Book Pro"...

There were such things called "Power Books" that were PPC based and pre-date the MBP line though. Its important to understand what hardware one is working with when troubleshooting.