Max2010 sp1 x64 Krakatoa1.6.1.43756 FumeFX1.2d
When applying a Density Gradient input channel to KCM on PRTFumeFX I receive the warning,
WRN: fumefx_particle_istream::load_voxels() - Failed to load some channels from .fxd file "M:\_CACHE_FumeFX\Untitled\2011_0202_1209\FumeFX01_0022.fxd"
WRN: The requested channels were: 0xa and the recieved channels were: 0x2
This non-functional unit seems restricted to FumeFX 1.x only it works fine with FumeFX 2.x
FYI, “received” is misspelled in the Log window, ‘i’ before ‘e’ except after ‘c’ 
Its saying its trying to load Fuel and Density from your sim (ie. 0xA), but its only able to load Fuel (0x2). Any ideas why Density isn’t available in that stream?
Ah, yep, smoke was disabled.
This happens in Fume 2.x too, I wasn’t thorough enough when I tried it on another machine that has ffx2.1 installed, the sim I tested it with had both fuel and smoke. When I disabled fuel in ffx2.1 I got the same warning.
So apparently you need both fuel and smoke enabled, is there anyway to change this behavior? When you only need fire on a heavy sim, if you have to include smoke too your sim time goes through the roof.
In order to create the DensityGradient channel you need to populate the Smoke voxels, so there isn’t any way to change that. I can however, make the error message less stupid!
I take what I can get
It would nice nice if it was more legible like “You have no Smoke/Density Channel DumbAss!”
Then I would know exactly what I needed to do 
and yes I should know better by now, that you need density for complete fume-compatibility…
You can still use the PRT FumeFX object without Smoke, you just can’t enable “Seed in Smoke” or attempt to use “Density” or “DensityGradient” via a KCM.
That I did know 
it was the Density/DensityGradient didn’t quite click. It should have, since it has density in the channel name. 