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That would cause the same version incompatibility problem.

Did you compile the class file with version 1.7 and try to execute it with version 1.6?
1.6 can not execute class files from 1.7

Can you get the full text of the error message:
Open a command prompt window, change to the folder with the jar file and enter:
java -jar THEJARFILENAME.jar

copy the contents of the command...

Some confusion here. Class names should start with uppercase letters

The class should have a main() method. Not a class.

Is the Main class in a package?
Is there a newline character after the...

Please copy the full text of the error message and paste it here.
What is in the manifest file that is in the jar file?
What are the locations/paths to the class files in the jar file?

Use the jar command that comes with the jdk

http://docs.oracle.com/javase/tutorial/deployment/jar/index.html