When I try to generate a test package without minified source code, I get this :

Code:
[INF] executing compass using system installed ruby runtimeNoMethodError on line ["23"] of C: undefined method `empty?' for nil:NilClass
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/sass-3.1.7/lib/sas
s/engine.rb:293:in `_render'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/sass-3.1.7/lib/sas
s/engine.rb:240:in `render'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/compiler.rb:140:in `block (2 levels) in compile'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/compiler.rb:126:in `timed'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/compiler.rb:139:in `block in compile'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/logger.rb:45:in `red'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/compiler.rb:138:in `compile'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/compiler.rb:118:in `compile_if_required'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/compiler.rb:103:in `block (2 levels) in run'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/compiler.rb:101:in `each'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/compiler.rb:101:in `block in run'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/compiler.rb:126:in `timed'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/compiler.rb:100:in `run'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/commands/update_project.rb:45:in `perform'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/commands/base.rb:18:in `execute'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/commands/project_base.rb:19:in `execute'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/exec/sub_command_ui.rb:43:in `perform!'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/lib
/compass/exec/sub_command_ui.rb:15:in `run!'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/bin
/compass:30:in `block in <top (required)>'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/bin
/compass:44:in `call'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/gems/compass-0.12.2/bin
/compass:44:in `<top (required)>'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/bin/compass:23:in `load
'
  C:/Sencha/Cmd/3.1.1.274/extensions/sencha-compass/gems/bin/compass:23:in `<mai
n>'
   remove ../css/app.css
[ERR]
[ERR] BUILD FAILED
[ERR] com.sencha.exceptions.ExProcess: compass process exited with non-zero code
 : 1
[ERR]
[ERR] Total time: 8 seconds
Please help me solve this problem. Thank you.