Uninstall from network

Hi all,

How do I uninstall an application from the network while installing it's newer version. I did this in the setup.ini, but not working. Please help.

[UNISABS05]
PRODUCT_NAME=Autodesk Building Systems 2005
INSTALL_CMD=msiexec.exe
INSTALL_CMD_ARGS= /x {5783F2D7-0306-0409-0002-0060B0CE6BBA} /qb

Thanks