arg+s21

hello, i am a beginner of cst, i had thought arg(S21) and Arg(S2,1) may be the same,but the result is not. and S21dB and |S2,1| in dB is the same. what is the Template Based Processing mean? what is the difference betweent S-parameter in it and Rsult Watch when you use Parameter Sweep?thank you. nysxf@yahoo.com.cn