Adobe Reader on iPad executing one line of javascript code

Please help, I am stuck on this weird issue.

I've some script which works perfectly on Adobe Reader (both windows & mac). However, for some reason on iPad (in Adobe reader app), it executes only first line of code and then no response. I am sure it's not code issue, 'cos I've tried different codes and even same code like alert.

So, basically If I put following in document open script, it will alert only once.

app.alert("Image Hidden Start - 1");
app.alert("Image Hidden Start -> 2");

Also, tried putting the same code in button on PDF and same behaviour.

Please help if somebody has any idea on how to solve this issue or if I need to do this differently. 

All I need to do is make document read only if an expiry date is passed and alert the user.