Some aircraft don't have enough elevator authority to enter a real stall if the are nose heavy CG. The wing fails to achieve the required angle of attack, and the plane mushes.
The solution for these kids of planes is not to enter the stall from MCA, as is typically taught. Rather enter from straight and level flight at Vx, and break int a full stall by sharply moving the yoke to its full aft position. This should result in a significant nose-up attitude and exceed the critical angle of attack, and you will see and feel a sharp break. Remain coordinated throughout the maneuver, and recover by releasing back pressure, and don't let the nose get too low.
This method can be adopted for aircraft that don't have enough elevator authority to do a turning stall.