you seem to be using semicolon ; instead of comma , in your Set and Collect values, maybe this was a typo?
Instead of setting a variable in the OnCheck property, can you use the Value property in your if statement? The If statement would look like this:
If(Checkbox1.Value=true,....)
You can achieve the collect in the If as well.
If(Checkbox1.Value=true, Collect(traject,{executive:"Mark"}))