In reply to sohan_b:
"a_s was the different sequence for i2c write and i was trying to write data in i2c registers. it turns out that i was passing too many arguments like conditional statements in an in-line constraints which was not working that’s why i was getting such error. also i was not giving constraints correctly.
And one more thing if we don’t pass any variable in for an ex. “obj.randomize()”, it will randomize all the variables declared as rand honoring constraints related to those variables."
Thanks for all the important informations.