Thanks Dave . I have 6 cover points in my design for which Functional coverage needs to be checked. I grouped 6 cover points under one cover group . then created new Instance ck and sampled it but it still giving me the same error -: " Cover group having sampling event is not allowed to be sampled using the predefined task ‘sample’ "
covergroup covport @(ganglion_if.cb);
option.auto_bin_max = 4; //Functional Coverage for Input top_left
coverpoint top_left;
coverpoint top_center;
coverpoint top_right;
coverpoint middle_left;
coverpoint middle_center;
coverpoint middle_right;
endgroup
covport ck = new()
initial begin
repeat(100)@(ganglion_if.cb)
begin
ck.sample();
end
endmodule