The two major difficulties, i. e., the excessive speed and the smallest preferred scale, encountered by wave-CISK as an explanation for the 40-50 day tropical intraseasonal oscillation (or the Madden-Julian oscillation, MJO), as demonstrated in many studies, are examined. In addition, wave-CISK is contrasted with a more promising framework for interpreting MJO recently proposed by Chao and Lin. The central cause for the two difficulties can be attributed to the convective heating formulation used. Also, depending on how one defines it, the wave-CISK concept as the foundation for interpreting MJO is at best inadequate and at worst erroneous.