The random number distribution you have specified either does not exist or is not supported.
Specify a valid random number distribution. It is possible that the syntax you have used is incorrect. When specifying a distribution for use with the Create Random Raster tool, at the command line, use a space-delimited string. For example, if you want a normal distribution with a mean of 0 and a standard deviation of 1, use the string "normal 0 1".