I have given my current employer 3 weeks notice for my resignation. A bonus was promised to staff for those who have completed evaluations between Oct. 1, 2004 through Oct. 1, 2005. My last day of employment is Oct. 14, 2005. The bonus will be issued on Nov 21, 2005. The employer states that because I will not be employed on Nov. 21, I am not eligible for the bonus. I have already earned this bonus. Can anyone help me to understand why I am not eligible or what I can do to get this bonus?

Any help is welcomed. Thanks in advance.

Generally speaking, it is legal for the employer to set such criteria for payment of a bonus. In defining wages, the guidelines listed in the link below does not specifically include earned bonuses. However, you might want to call the state Dept. of Labor at (803) 896-7756 to inquire for sure.
http://www.llr.state.sc.us/Labor/index.asp?file=wagesmain.htm