I'm trying to map new fields in Leads to Potentials and Contacts. I'm getting an error message that says, "Parent field No of Employees of length 9 should be less than or equal to Potential's field No. Employees of length 5." 

When I go into Leads to edit the field, I'm unable to change the values. It is saying it is a system defined value. It is also set to 1, even though we can edit many digits. For example I can enter, 40,000 in the field.  I see the following: