AD5934 - Problem to start a measurement

Not sure if this is relevant specifically to the values in the status register, but are you enabling the use of the external oscillator by writing 0 into D3 in the 16-bit control register (Register Address 0x80 and Register Address 0x81)? Paradoxically, power-on value of D3 is 1, which is selecting the built-in internal oscillator as the source of clock for the chip, but the AD5934 does not have the built-in internal oscillator, so it cannot function until the use of the external oscillator is enabled.

Not sure if this is relevant specifically to the values in the status register, but are you enabling the use of the external oscillator by writing 0 into D3 in the 16-bit control register (Register Address 0x80 and Register Address 0x81)? Paradoxically, power-on value of D3 is 1, which is selecting the built-in internal oscillator as the source of clock for the chip, but the AD5934 does not have the built-in internal oscillator, so it cannot function until the use of the external oscillator is enabled.