Chinese Acad Sci, Grad Sch, Beijing 100039, Peoples R China
; Nankai Univ, Dept Phys, Tianjin 300071, Peoples R China
; Chinese Acad Sci, Inst Theoret Phys, Beijing 100080, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
While deriving the effective potential by calculating the elastic scattering amplitude between quark-antiquark, one would encounter the ordering problem. Even the hermiticity requirement is considered, various ordering schemes may still lead to different numerical results. We investigate this issue and present the preliminary results, then make some discussions.