Why do I get the error java.lang.NoClassDefFoundError: Could not initialize class net.sf.jasperreports.engine.DefaultJasperReportsContext at run time

[mamartinez]

I upgraded to jasperreports 6.1.0 and now I get the error "java.lang.NoClassDefFoundError: Could not initialize class net.sf.jasperreports.engine.DefaultJasperReportsContext" at run time.  This class does exists.  

[hozawa]

You're probably missing a jar in your classpath.

[mamartinez]

When I run my java application through netbeans, it works fine.  then when I build and sign my jar and run on server I get this error.  Do you know why is it that when I was using a previous jasper library version I did not have this problem?