Strange sorting of time groups

Is there a solution to the problem that time groups get sorted in a very strange way...in the web gui and in the extensions_additional.conf?

e.g. this is my holiday calendar

include => timeconditions-custom
exten => 1,1,GotoIfTime(08:00-18:00|mon-fri|*|*?ivr-2,s,1)
exten => 1,n,GotoIfTime(08:00-12:00|sat|*|*?ivr-2,s,1)
exten => 1,n,Goto(app-announcement-1,s,1)
exten => 2,1,GotoIfTime(*|*|8|dec?app-announcement-1,s,1)
exten => 2,n,GotoIfTime(*|*|6|jan?app-announcement-1,s,1)
exten => 2,n,GotoIfTime(*|*|26|oct?app-announcement-1,s,1)
exten => 2,n,GotoIfTime(*|*|25|dec?app-announcement-1,s,1)
exten => 2,n,GotoIfTime(*|*|21|may?app-announcement-1,s,1)
exten => 2,n,GotoIfTime(*|*|1|may?app-announcement-1,s,1)
exten => 2,n,GotoIfTime(*|*|1|jun?app-announcement-1,s,1)
exten => 2,n,GotoIfTime(*|*|1|jan?app-announcement-1,s,1)
exten => 2,n,GotoIfTime(*|*|15|aug?app-announcement-1,s,1)
exten => 2,n,GotoIfTime(*|*|13|apr?app-announcement-1,s,1)
exten => 2,n,GotoIfTime(*|*|11|jun?app-announcement-1,s,1)
exten => 2,n,GotoIfTime(*|*|26|dec?app-announcement-1,s,1)

I entered the holidays starting with January 1st. Why is Trixbox CE (2.8) messing around with the time group entries? It`s even more annoying in the Web-GUI...there, June 11 comes first, followed by April 13...
Any idea...how to fix it?

Thanks
Reinhard