Peoplesoft shows no popup message intermittently

Hi~

The Peoplesoft env I use like following :

Peoplesoft HCM 9.1

Peopletools 8.50.09

weblogic, tuxedo

SunOS Spark 5.10

Oracle Database 11.2.0.3

It's a standard page and normal until recently.

When I click the save button the message popup box does not show sometimes. So, the user cannot notice whether it is saved or not. Actually it is not saved when the message box does not showed.

There are no special messages on appserver log file, webserver log file.

How can I detect the cause of the issue?

I found similar bug report but it on PT8.53.

"20019907 : ERROR POP-UP MESSAGES NOT DISPLAYING INTERMITTENTLY IN PEOPLESOFT PAGES"