Running count calculation to find duplicate values

[pocoloco]

I am trying to run a count calculation on a particular column that has duplicate values.  For instance -1 , 1, 2, etc.  If I create a calculated field and try using the running count function I get a count of all the values in the column instead of a repeating count for the different values or group of numbers.  For example, if I have 10 (-1) values I would like the column to display a count from 1 to 10 for this particular value, and then have a new count for another value.  Any suggestions on how to solve this problem??