I figured it out. I did not put the Class-Path entry into the jar file manifest. I had the Main-Class ok, I did not realize that I needed to fill in the Class-path as well. Example below.
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.6.5
Created-By: 1.5.0_09-b03 (Sun Microsystems Inc.)
Main-Class: com.sftest.prodconvert.Converter
Class-Path: lib/activation-1.1.jar lib/aopalliance-1.0.jar lib/commons
-logging-1.1.jar lib/commons-pool-1.3.jar lib/jaxb-api.jar lib/jaxb-i
mpl.jar lib/jaxb-xjc.jar lib/jdom-1.0.jar lib/jsr173_api.jar lib/juni
t-4.0.jar lib/log4j-1.2.14.jar lib/poi-3.0-FINAL.jar lib/saxpath-1.0-
FCS.jar lib/sjsxp.jar lib/spring-2.0.5.jar