How exactly are you trying to deploy? Is it via BLPackage creation or simle exe deployment and then initiating using a script? Make sure this is not a zipped package or a corrupt package.
Also, check if you are sending a valid EXE, MSI package and not Unix script based.
Typically you need to do some research when installing an application. What type of installer does it use? What are the command line switches to install it silently? Is there a different version for 32/64 bit?
According to this
For the .exe installer 7-Zip uses the NSIS installer by Nullsoft.
There is also an MSI installer with it's own switches.
So can you be more specific about how you are installing 7-Zip? There are many ways in BSA.