TPS630250: Vout instable

Hello,

I have implemented  the circuit that fallow in link:

webench.ti.com/.../65

I have checking de follows:
•    when put ~4V in Vin i have ~3.0V in Vout
•    If change Vin betweem 3-4.1V the Vout change between ~2.5-3.1V

Do you know what be happening?

Thanks Roberto