I have a problem with PLL HMC830.

I program HMC830 with parameters as follows :

Integer Mode for output = 50 Mhz (XTAL = 50 Mhz)

HMC830_HMC_Write(0, 0x20); // soft reset and = A7975 in read
delay (20);
HMC830_HMC_Write(1, 0x2);
HMC830_HMC_Write(2, 0x1);
HMC830_HMC_Write(5, 0x1628);
HMC830_HMC_Write(5, 0x60A0);
HMC830_HMC_Write(5, 0x7C10);
HMC830_HMC_Write(5, 0x2898);
HMC830_HMC_Write(5, 0x0);

delay (10);

HMC830_HMC_Write(6, 0x0303CA);
HMC830_HMC_Write(7, 0x00014D);
HMC830_HMC_Write(8, 0xC1BEFF); = BEFF in read
HMC830_HMC_Write(9, 0x153FFF); = BFFF in read
HMC830_HMC_Write(10, 0x002046);
HMC830_HMC_Write(11, 0x07C061);
HMC830_HMC_Write(15, 0x000081);

HMC830_HMC_Write(3, 0x0038);
HMC830_HMC_Write(4, 0x0000);
delay (10);

XTAl 50 Mhz

SPI bus works well but i obtain 50.88 Mhz (drift) instead of 50.00 Mhz at OUTPUT_N.

In debug mode , ie Mute Reg05 =0x10 and with Reg15 as follows :

Reg15 = 0xC9 (Ref divider output) : 50 Mhz
Reg15 = 0xCA (VCO divider output) : no signal...

Reg11 = 7C461 (Force CP down) : i have 500 mV on pin CP
Reg11 = 7C261 (Force CP UP) : i have 5V on pin CP
Reg11 = 7C861 (Force CP mid rail) : i have 2.5 V on pin CP

This board has two powers i measured 3.3V and 5.0 V (HMC1060).
I think the N divider doesn't works well ?

Please could you help me ?