Error about Action Sequence

When I installed Pentaho,I can run pentaho-solutions/bi-developers/getting-started/HelloWorld.xaction.

1.but I copied HelloWorld.xaction to HelloWorld555.xaction. I can't run HelloWorld555.xaction. the error as bellow:
Error: SolutionEngine.ERROR_0007 - Action sequence run failed (org.pentaho.platform.engine.services.solution.SolutionEngine)
Debug: begin run bi-developers/getting-started/HelloWorld555.xaction (org.pentaho.platform.engine.services.solution.SolutionEngine)
Debug: get context and data(org.pentaho.platform.engine.services.solution.SolutionEngine)
Debug: loadding action sequence file (org.pentaho.platform.engine.services.solution.SolutionEngine)
Error: SolutionEngine.ERROR_0007 - Action sequence run failed (org.pentaho.platform.engine.services.solution.SolutionEngine)

Server Version: Pentaho Platform Engine Core 4.8.0-stable.51169

2. when I edited HelloWorld.xaction, but the output is not changed!

would you tell me how to get it ?