random number problem...

Hi, I've written a picture rotation script, file paths are stored in a file and are called depending on a random number generator.. The problem is that out of 14 possible numbers only 7 are been generated. the code I'm using is... srand ( (double) microtime()*10000000); $numbertodisplay = rand(0, (($no_items)-1)); The variable $numbertodisplay only ever takes the values 0,2,4,6,8,10,12. Is there a reason that the only numbers produced are even? Thanks for any help.. James