You found GSPOT - that's the identifier I was going to recommend...
Some DVD Players CANNOT accept CD-R media - though they will sometimes accept CD-RW.
An additional laser is needed for CD-R, but apparently CD-RW can be read by a DVD laser.
I assume you made a VCD which your PC accepts as such? http://www.dvdrhelp.com/vcd
Get the sample from here - using the PAL (25 FPS) or NTSC (30 FPS) as appropriate - this will rule out any problems in your preparation of the VCD, as it will burn a standards-compliant VCD
To test SVCD similar test samples are on this page http://www.dvdrhelp.com/svcd
If your player cannot play these on CD-R media, try CD-RW.