MIB contains errors when smidump

Hi all,
I got error when i using import.rb to convert a mib file as following:

/opt/logstash/vendor/bundle/jruby/1.9/gems/snmp-1.2.0# ruby -d import.rb convermib/

Exception LoadError' at /usr/lib/ruby/2.1.0/rubygems.rb:1203 - cannot load such file -- rubygems/defaults/ruby ExceptionNameError' at /usr/lib/ruby/2.1.0/psych/class_loader.rb:67 - uninitialized constant BigDecimal
Exception NameError' at /usr/lib/ruby/2.1.0/psych/class_loader.rb:67 - uninitialized constant DateTime ExceptionNameError' at /usr/lib/ruby/2.1.0/psych/core_ext.rb:16 - method to_yaml' not defined in Object ExceptionNameError' at /usr/lib/ruby/2.1.0/psych/core_ext.rb:29 - method yaml_as' not defined in Module ExceptionNameError' at /usr/lib/ruby/2.1.0/psych/deprecated.rb:81 - undefined method to_yaml_properties' for classObject'
convermib/
convermib//CERENT-FC-MIB.mib
Exception Errno::EEXIST' at /usr/lib/ruby/2.1.0/fileutils.rb:250 - File exists @ dir_s_mkdir - /opt/logstash/vendor/bundle/jruby/1.9/gems/snmp-1.2.0/data/ruby/snmp/mibs smidump: moduleconvermib//CERENT-FC-MIB.mib' contains errors, expect flawed output

Anyone can help or guide me here? how to fix that?
As always, many thanks for your help!