Matching Sony remote controls

I bought this Sony DVD player, DVP-NS700H as a floor model, and it came with a "DVD remote" RMT-D243A.

All the research I've done says I have the correct remote, but my DVD ignores it.

I know the remote isn't dead because its TV buttons operate my Sony TV.

I know the DVD is OK because it works perfectly from the "DVD" buttons on my other Sony remotes (RM-U262 and RM-YD017) that happen to have DVD functions.

I'm told that Sony has some sort of way for users to tell certain A/V stuff to use alternate codes (so you can for example have two VCRs). But I can't find the secret incantations to make my RMT-D234A talk to my DVP-NS700H player. The DVD owners manual has no clues for me.

This isn't a disaster; the DVD works perfectly from my TV's remote but it bugs me that it ignores the remote that supposedly came with it.

Any hints on how to switch codes to match the DVD player? Or a definitive answer whether I have the wrong remote?

After even more research.... solved

I did another search and found the RMT-D234A was actually supposed to ship with a different DVD, actually the RDR-GX355 recorder. So much for the sales critter who insisted..... not to blame him much, the two look almost the same.

So I located that recorder's manual, and found that some Sony remotes do have multiple "modes". You can own up to three DVDs and operate them independently. That rumor being verified, I found that the RMT-243A remote defaulted to "mode 3". I had to press and hold the "enter" key and then press my choice of "1","2", or "3" to select another mode. My player works with "mode 1".

There was nothing about this in my DVD player manual; maybe (probably?) it isn't programmable.