How to de-embed the effect of additionally attached semi-rigid coaxial cable

I have to de-embed the effect of additionally attached semi-rigid coaxial cable on the RF cables for the two port measurements. After simple two port calibration (without semi-rigid cable) of VNA (picture 1), the results are ok. After that i attached the semi-rigid cable and apply the automatic port extension in VNA on Port 1 for OPEN case, but the effect of the additionally attached semi-rigid cable is not completely removed. Any suggestions to remove this effect completely? Thanks !