Batch alphanumeric generator , need help to solve bugs

I am trying to create an Alphanumeric generator using batch script, it will generate randomly 4 to 10 letters or numbers. The problem is that i can not see anything on the screen while i still generate random numbers! I need some help , i have been trying to find a solution for several hours!

Thanks in advance!

Here we go with the code: http://ift.tt/1pI2vZs

for some reason when i post here the code there's a bit of a broblem with the lines, so ... i made a website quickly : http://ift.tt/1pI2vZs