Graph not showing German Characters

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Hello,
I am using Cacti 0.8.8a on Debian wheezy on host Raspberry Pi
since the last system update ( sudo apt-get update/upgrade) the graphs do not show German characters in graphs view.
In the exported views the characters are still here.

Here is the debugged rrd code for the display in graphs view:
AREA:cdefbh#FFF200FF:'Flammt. Fhler':STACK GPRINT:cdefbi:MAX:' %1.0lf' AREA:cdefbj#FFFFFFFF:'':STACK AREA:cdefca#FF00FFFF:'Kesselsensor':STACK GPRINT:cdefcb:MAX:' %1.0lf' AREA:cdefcc#FFFFFFFF:'':STACK AREA:cdefcd#7CB3F1FF:'STB':STACK GPRINT:cdefce:MAX:' %1.0lf\n' AREA:cdefcf#FFFFFFFF:'':STACK AREA:cdefcg#FF7D00FF:'keine Pellets':STACK GPRINT:cdefch:MAX:' %1.0lf' AREA:cdefci#FFFFFFFF:'':STACK AREA:cdefcj#942D0CFF:'berhitzung':STACK GPRINT:cdefda:MAX:' %1.0lf' AREA:cdefdb#FFFFFF7F:'':STACK AREA:cdefdc#A150AAFF:'Ke T zu niedrig':STACK GPRINT:cdefdd:MAX:' %1.0lf' AREA:cdefde#FFFFFFFF:'':STACK AREA:cdefdf#8F928633:'(Luftklappe)':STACK GPRINT:cdefdg:MAX:' %1.0lf\n' AREA:cdefdh#FFFFFFFF:'':STACK AREA:cdefdi#6EA100FF:'Frdersyst':STACK GPRINT:cdefdj:MAX:' %1.0lf'

and here for the exported graph:
AREA:cdefbh#FFF200FF:'Flammt. Fühler':STACK GPRINT:cdefbi:MAX:' %1.0lf' AREA:cdefbj#FFFFFFFF:'':STACK AREA:cdefca#FF00FFFF:'Kesselsensor':STACK GPRINT:cdefcb:MAX:' %1.0lf' AREA:cdefcc#FFFFFFFF:'':STACK AREA:cdefcd#7CB3F1FF:'STB':STACK GPRINT:cdefce:MAX:' %1.0lf\n' AREA:cdefcf#FFFFFFFF:'':STACK AREA:cdefcg#FF7D00FF:'keine Pellets':STACK GPRINT:cdefch:MAX:' %1.0lf' AREA:cdefci#FFFFFFFF:'':STACK AREA:cdefcj#942D0CFF:'Überhitzung':STACK GPRINT:cdefda:MAX:' %1.0lf' AREA:cdefdb#FFFFFF7F:'':STACK AREA:cdefdc#A150AAFF:'Ke T zu niedrig':STACK GPRINT:cdefdd:MAX:' %1.0lf' AREA:cdefde#FFFFFFFF:'':STACK AREA:cdefdf#8F928633:'(Luftklappe)':STACK GPRINT:cdefdg:MAX:' %1.0lf\n' AREA:cdefdh#FFFFFFFF:'':STACK AREA:cdefdi#6EA100FF:'Fördersyst':STACK GPRINT:cdefdj:MAX:' %1.0lf'

Can anybody tell me, where in code this was made worse?