Are you trying to only display the records that are '1' or just do a count of them?
To only display, try {table.Paid}='1' in the Record Selection formula editor.
If you only want to do a count and display all records, do nothing to Record Selection and create a Running Total where the FIELD TO SUMMARIZE is {table.Paid}, the TYPE OF SUMMARY is COUNT, EVALUATE the total FOR EACH RECORD, and RESET as you need (NEVER if you are looking for a grand total for the whole report or CHANGE ON GROUP for Group Totals).