The RISAT C2 matrix elements produced from PolSARPro are not opening in SNAP

I have used PolSARPro 5.1 Beta Version to generate C2 matrix of RISAT FRS1 SLC product. I am using SNAP 6.0. I am able to import the C2 elements generated by PolSARPro 5.0 Version.
Is it the issue with SNAP or PolSARPRo?