Finalising DVD-RW discs ,help!

Hi, can you help me please, I bought a Sony RDR-Hx750 recorder and am having a problem doing so called finalising DVD-RW discs so they may play on another DVD player. Have followed the instructions as per the Sony manual, and cannot get the discs to play on another brand of player, play on the Sony no problem, but no go anywhere else. Iv'e tried new discs, formatted discs and closely followed Sony instructions, the odd thing is that the first few times I recorded,the discs played on another DVD no problem, not now.I've let them run out,all sorts of things. Need advise..many thanks..Lang