If your DUT is an antenna and if there is a cable between the antenna and the impedance bridge, you must adjust the phase of the V(reflected) according to the electrical length of the cable. Suppose the electrical length is alpha times the wavelength, then the vector V(reflected) must be advanced for twice alpha times twice pi [rad] to obtain the feed point impedance of the antenna.
It is a counter clockwise movement of the vector, and is said to be “Towards the Lord” in Smith Chart terminology.