Two LICET transitions in Cs-Sr systems are suggested and the results of numerical calculations of the transition probability and collisional crosssection are obtained respectively from our four-level model and the conventional three-level model. Comparisons of these results prove the theoretical prediction that if the frequency difference |ω21| is comparable to |ω43|, the three-level theory has great error in describing the LICET transition, while the four-level theory can describe all cases of LICET process perfectly.