Android : how to use proguard in android for export apk

what is '-injar' ? what is mean?

Proguard returned with error code 1. See console

proguard.ParseException: Expecting class member name before '-injars' in argument number 7
at proguard.ConfigurationParser.readNextWord(ConfigurationParser.java:1133)
at proguard.ConfigurationParser.readNextWord(ConfigurationParser.java:1117)
at proguard.ConfigurationParser.parseMemberSpecificationArguments(ConfigurationParser.java:845)
at proguard.ConfigurationParser.parseClassSpecificationArguments(ConfigurationParser.java:697)
at proguard.ConfigurationParser.parseKeepClassSpecificationArguments(ConfigurationParser.java:490)
at proguard.ConfigurationParser.parse(ConfigurationParser.java:139)
at proguard.ProGuard.main(ProGuard.java:484)

I was add extenal library in proguard-project.txt

but cannot export apk.... How to slove it?

plz slove this problem....CodeObfuscation