Random(Number4,0:2:1) Should assign randomly 0,1 or 2. However, 2 is never assigned, in this case, the results are always 0's and 1's and never 2.
Random(Number4,1:3:1) Should assign randomly 1,2 or 3. However, 3 is never assigned, in this case, the results are always 1's and 2's and never 3.