EXS 24 Logic Sampler Users Group

Hi,

By going Library/Application Support/Logic there is the Sampler 
Instruments folder.
In the Sampler Instruments folder are the sampler instrument library 
files in exs format.
I have no problem loading these into the EXS.
Also if  going Library/Application Support/Logic there is the EXS 
Factory Samples folder.
And in this folder are different instruments in aiff format than in the 
Sampler Instruments folder.
I cannot load these aiff files into the EXS24 even if I put them into 
the Sampler Instruments folder.
I haven't found any mention of this in the EXS24 mkII chapter of the 
Pro 7 Plug-in Reference manual although it says that the EXS24 is 
compatible with AIFF files.
Is this possible and if so, how is it accomplished?

Thanks for any enlightenment,
Jim