Passing variables to an SSIS package

Hello,
I am trying to pass a variable before run time of an integration
package, that would tell that package which other packages to run,
based on "precedence constraint" > Expression > @listid == 16.

The way it's set up is an sql task, without an sql query, is first to
execute. From this sql task, four output connections lead to 4
different packages, each one having a different precedence constraint
value from @listid. Whichever listid value is entered before run time,
that package would be run.

With this setup, the package executes without errors, but nothing
occurs.

Can anyone help?

Thank you,
Krzysztof