Some linux servers can untar files but not unzip files. You may need to install unzip on your server to do this.

Unzip can be found at: ftp://ftp.info-zip.org/pub/infozip/src/unzip541.tar.gz

To install:
1. log into ssh
2. Switch to root

#su -

3. issue these commands

#gunzip unzip541.tar.gz
#tar -xvf unzip541.tar.gz
#cd unzip-5.41
#make -f unix/Makefile generic
#make -f unix/Makefile install