BINGO!
I followed your thoughts again and you were correct on your diagnose. This box i have is running PO, which explains the old source.
what comes to the necessity of upgrading it.
The upgrading process was successful to the HEAD version of acs-core 5.5. As I expected however, when i try to ugrade pkg acs-tcl...,
once i restart aolserver it gets a bunch of errors of "API non-exists" such as subsite APIs and etc.
The bottom line is we figure out the issue. thanks!
Although i will need to handle another consequent new errors that showed up.
it helped!
