Is HDMI 1.4 backwards compatible with 1.3? I'm installing a Hitachi MS-1 switcher, and it's HDMI output works fine with an HDMI v1.3 cable, but not with a cable v1.4.  I've tested the v1.4 cable on a different output device (DVD player) and it works fine.  I've also tried two different display devices (monitor and projector).

My question is:  Is HDMI v1.4 supposed to be fully backwards compatible, or are there some caveats?

Also, has anyone else encountered any equipment that worked with HDMI v1.3 but not v1.4?
A 1.4 cable should work fine with a 1.3 signal, however an HDMI 1.4 signal will not work with an HDMI 1.3 cable or an HDMI 1.3 output unless the source is capable of using a prior standard.