Trying to write skill code to return a layer's color

Hi,

I'm trying to write code to get each layer's color.
The documentation indicates that there is a "fillColors" attribute for a layer, but I don't see that attribute in a sample that I have.

techFileID = techGetTechFile(cv)
nth( 16 techFileID->layers )->??

OUTPUTS THIS:
(db:0x1773e42a objType "physicalLayer" prop
(db:0x1773d831 db:0x1773d82f db:0x1773d834 db:0x1773d832)
groupMembers nil number 34 name
"Metal2" abbrev "Metal2" lps
(db:0x21714f50 db:0x21715070 db:0x21715190 db:0x217152b0 db:0x21718f70
db:0x2171b7f0 db:0x21722750 db:0x21725ec0 db:0x21725fe0 db:0x217293d0
db:0x217294f0 db:0x21729610
)
incompatibleLayerNames nil backside nil material
"metal" valid t allowSetToValid t
allowSetToValidInSession t
)

nth( 16 techFileID->layers )->fillColors

OUTPUTS THIS:
nil

nth( 16 techFileID->layers )->outlineColors

OUTPUTS THIS:
nil

But the layer is visible.
Can someone tell me what I need to do to get a layer's rgb color?