you need to manualy download
4 .jar files
they are
and put them in the lib file of voltz or tekkit lite and make sure u delete the orignial .jar files that are in there.
http://files.minecraftforge.net/fmllibs/bcprov-jdk15on-147.jar
http://files.minecraftforge.net/fmllibs/asm-all-4.0.jar
http://files.minecraftforge.net/fmllibs/guava-12.0.1.jar
http://files.minecraftforge.net/fmllibs/argo-2.25.jar