[Shapelib] shpproj help

[Ken S. Elvehjem]

Hi,

I have a set of shapefiles that are in what I have always been told are 
"unprojected longitude & latitude."

X & Y coordinates are in decimal degrees ( -92.5173861 x 42. 9431848)  with 
a datum of WGS84

I am trying to use shpproj to convert these files to UTM Zone data (Zone 15, 
in my example) for some further analysis.

The following don't work:

shpproj jack jackson-soils-UTM -i=geographic -o="proj=utm zone=15 units=m"
shpproj jack jackson-soils-UTM -o="proj=utm zone=15 units=m"

The processis aborted with the note, "unable to process projection, exiting"

I suspect that some data files may be missing, but I have no way of figuring 
that out.

BTW, the "proj"  directive "works" but doesn't give me any good clues 
either.

Any suggestions would be greatly appreciated.

Ken