Sharepoint not showing calender content on internet but ok in Intranet

We have a ISA server in between the Sharepoint and internet. and For 2 years, I could not resovle this mystery problem, the Calender shows nothing on external network but working perfectly internally.

After 2 years, I accidentally found an post regarding the Menu Navigation not working on External network but internally.
http://blog.blksthl.com/2013/12/16/fixing-the-scriptresource-axd-errors-500-internal-server-error/

Since my gate is ISA 2006, which is old, however I found the similar area under
Configuration -> Add ons->Compression Filter -> Enalbed.
Bang! Problem solved.

Also the navigation dropdown which was blocked for last 2 years was solved as well.
Thank you so much
Thomas Balkeståhl
who is the author of
http://blog.blksthl.com/2013/12/16/fixing-the-scriptresource-axd-errors-500-internal-server-error/