You mean, selecting a maximum value in a calendar object at the end of a reload? There are no UI objects during script execution, so you cannot make selections. Moreover, the useful triggers are not available in a Server environment. See the last part of "Macro Trigger Limitations" in Using Macros in QV Documents on the QV-Server ‒ QlikView (or in the QlikView Reference Manual).
What you can do is define a Select in Field Action and attach it to the OnOpen trigger in your document. That will work.
Because a document that is getting reloaded/distributed by the Publisher (that's what the Publisher does) will not have the OnOpen trigger firing. OnOpen will fire whenever a user opens a document in the AccessPoint or in QV Desktop. Sorry.
Another possible technique could be to set a variable and let the Report use that variable in some way. Not sure about what you want to do with the MAX value.