Java SE (Java Platform, Standard Edition)

Hi, I'm not very experienced with java and am trying to create a voice recording applet. I have created the applet, but when I attach it to my htm file using the <applet> tags, it keeps coming up with the error Applet Transmitter Notinited, then it says Loading Java Applet Failed... The error is as follows:

java.lang.NoClassDefFoundError: javax/media/format/UnsupportedFormatException
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
at java.lang.Class.getConstructor0(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at sun.applet.AppletPanel.createApplet(Unknown Source)
at sun.plugin.AppletViewer.createApplet(Unknown Source)
at sun.applet.AppletPanel.runLoader(Unknown Source)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

Please could someone help me.....would be very much appreciated :)
Thanks in advance. x