Error in Phase lock loop using ic 4046

[Wasif]

I want to implement phase lock loop circuit using ic 4046 for 50 hz. But I have a problem that my output frequency is oscillating around input frequency which is 50hz.... Attached is the circuit....
Anyone can solve the problem....

 

[kellys_eye]

Time constant of the low pass filter.

 

[Wasif]

11 sec by formula t=(r1+r2)c

 

[Wasif]

I picked filter value from circuit available online