please can anyone explain this error in logcat
<pre><code>06-26 17:07:09.898: E/AndroidRuntime(380): FATAL EXCEPTION: main
06-26 17:07:09.898: E/AndroidRuntime(380): java.lang.NoClassDefFoundError: org.mythrii.email.Mail
06-26 17:07:09.898: E/AndroidRuntime(380):  at org.mythrii.email.Email$1.onClick(Email.java:19)
06-26 17:07:09.898: E/AndroidRuntime(380):  at android.view.View.performClick(View.java:2485)
06-26 17:07:09.898: E/AndroidRuntime(380):  at android.view.View$PerformClick.run(View.java:9080)
06-26 17:07:09.898: E/AndroidRuntime(380):  at android.os.Handler.handleCallback(Handler.java:587)
06-26 17:07:09.898: E/AndroidRuntime(380):  at android.os.Handler.dispatchMessage(Handler.java:92)
06-26 17:07:09.898: E/AndroidRuntime(380):  at android.os.Looper.loop(Looper.java:123)
06-26 17:07:09.898: E/AndroidRuntime(380):  at android.app.ActivityThread.main(ActivityThread.java:3683)
06-26 17:07:09.898: E/AndroidRuntime(380):  at java.lang.reflect.Method.invokeNative(Native Method)
06-26 17:07:09.898: E/AndroidRuntime(380):  at java.lang.reflect.Method.invoke(Method.java:507)
06-26 17:07:09.898: E/AndroidRuntime(380):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
06-26 17:07:09.898: E/AndroidRuntime(380):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
06-26 17:07:09.898: E/AndroidRuntime(380):  at dalvik.system.NativeStart.main(Native Method)
</code></pre>
