UBB.Developers Forums UBB.classic V6 MultiHack Mods [6.0x] Chat Mod 1.0.23

after I upgraded to whosonline 3.9 I get this error as soon as I press the link of the chat
Software error:
Undefined subroutine &main::WriteUserSession called at /home/virtual/mydomain.ru/html/cgi-bin/ultimatebb.cgi line 368.

the script there is
#print header(-cookie=>[$cookie1, $cookie2, $cookie3]);
print header(
-cookie=>[$cookie1, $cookie2, $cookie3],
-charset => "$masterCharset");

} else {
#line 368
unless (($ubb eq 'submit_registration') || ($ubb eq 'edit_profile')) {

any ideas