problem simulating CD4046 with ADIsimPE

i have been trying to simulate cd4046 with ADIsimPE but the IC just doesnt work at 15V power supply. I have calculated the values of R1,R2, C1 susch that the frequency range is between 32 to 33 Khz. I am checking the values of f min bygiving no input signal. The simulation works just fine when the power supply is under 10 V, the moment i go above 10V it just gives absurd results .I want to run the IC on 15V. I just cant figure out why this is happening.

Thanks