No, that's not it. I am only running this report on a single MDB that has less than 10 sites. It seems like when I try to add a new column to the report using the attribure :idate, or :rdate, or another UDA, I get this error message. Right now the report contains, 16 columns. I wonder if there is a limit on how many UDA's you can report on. I wouldn't think so, but this seems to be an issue. If I add a column (column 18) for REV, the report will still run and come out just fine. And this is a file output to a .csv file.
That is too many columns. Currently the report can handle only up to 256 characters. If you are using PDMS 12, you can create a custom pml report that can handle many columns.