You don't have to upgrade your copy of Mathematica, or purchase anything new. The problem with your notebook appeared to be the final arrow in the Show statement.
Keep in mind that the Front End has several palettes which contain arrows. However, only one specific arrow will be understood by the Kernel during evaluation. My advice is to use only the arrows on the BasicInput palette.
Please see the attached notebook for my methodology in solving this problem.
Attachment: complex2.nb, URL: ,