Mystic Reaper, the trans isomer of the complex [CoCl2(en)2] does not show optical isomerism. You can understand it as a general rule that for coordination number 6 complexes, having two bidentate ligands, which is ethylene diamine or en in this case, the cis- isomer is optically active and trans- isomer is always optically inactive. Since the trans- isomer or the trans- form does not show optical activity, therefore it can't show optical isomerism and can't exist as dextrorotary and levorotatory forms.