Using LFT of two SISO systems yields system with no input/no ouput

Hey guys I am using an 'lft' command to connect two SISO systems say sys1 and sys2, syntax is N = lft(sys1,sys2); now the output N is shown to have no input and no output. For example if the number of states are 2, then N.b is 2*0 matrix and N.c is 0*2 matrix. What does it physically mean? Does the loop is closed and there is no free input/output channel available?