I am almost positive you have at least 2 tables in this report. They will be from the same DB.
Likely you have a CONTACTS table and a PHONE table which are joined togther as an inner join on the CONTACT ID field.
IN your Field explorer (top of your tree), expand the Database Fields.
Now you should see 2 or more table names (CONTACTS and PHONES). If you expand the table names you will see the fields/columns in each table.
Here is what I am pretty sure is happening.
Crystal does not enforce joins just by making the join (like in SQL). You have to tell it to be enforced in the join set up or it will enforce the join when you use fields from both tables anywhere in the report. So when you exlude the phone number all the contact names appear. As soon as you use the phone number the join is enforced and the names disappear becase ther eis no row in the PHONE table to match to any row in the CONTACTS table.
Is this more on track?
Edited by DBlank - 25 Oct 2010 at 8:48am