Your problem is that you are continuously reseeding the Random Number Generator using the SRND function. This is a very very very bad idea. Don't do it.

You should seed the RNG only once in your script, unless you are deliberately intending to produce repeatable sequences. If you keep reseeding it, you screw up the calculation that makes the RNG appear to return random numbers.

Also, after seeding the RNG you should always discard the first number that RND() returns, as many seeds produce the same first number.