Asterik IP-PBX Statistics (SIP/IAX2 protocols) Problme!

[mrysoft]

Hello,
I Download and installed asx-stats-0.3.0 On My Cacti Server.
But When I want To create graphs for device asterisk Show Me This

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Data Query [asx-stats - Asterisk Statistics]
This data query returned 0 rows, perhaps there was a problem executing this data query. You can run this data query in debug mode to get more information.
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and Debug Mode Say Me This Log:

Data Query Debug Information
+ Running data query [14].
+ Found type = '4' [Script Query].
+ Found data query XML file at '/usr/share/cacti/site/resource/script_queries/asx-stats.xml'
+ XML file parsed ok.
+ <arg_num_indexes> missing in XML file, 'Index Count Changed' emulated by counting arg_index entries
+ Executing script for list of indexes '/usr/share/cacti/site/scripts/asx-stats.py 192.168.20.101 --index' Index Count: 0
+ Executing script query '/usr/share/cacti/site/scripts/asx-stats.py 192.168.20.101 --query device'

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My Cacti Server With Version 0.8.8b.
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plz help me that how can i resolve it?