1. Some JavaScript actions are not allowed to be executed until the form hasn't be initalized completely, like event.target.closeDoc(true); for example.
2. This was only a hint for you to avoid wasting time with programming different form actions depending of the users Reader version.
You can combine the version check with another action, like lauching the URL where the newest Reader can be downloaded.
That's very user friendly, I think.
if (typeof(app.viewerVersion) != "undefined")
if (app.viewerVersion < 9.0)
{
if(xfa.host.messageBox("Sorry, but this form requires Adobe Reader version 8.1 or higher!\rPress OK to close the form and download the newest version of Adobe Reader (freeware).\r\rThank you for your cooperation!", "Attention",1,0)==1)
{
event.target.closeDoc(true);
app.launchURL("http://get.adobe.com/de/reader/", true);
}
}