You can make the parameter a string and that way it accepts a comma delimited list of numbers. For the record selection filter to test if a number is in the list, use the following sample code:

CStr({table.yourfield},"#") IN Split({?parameter},",");

This functions splits the string into an array using the comma separator and then it tests if the field is in the array.

I actually wrote about this exact problem on page 190 of my book Crystal Reports Encyclopedia.

I got it! I used the string, but never made the parameter a string! Armature mistake! Thanks!!!