Foreign Key Constraints in Toad for Oracle

Hello, I am working on a simple Customer database which requires about five tables most of which have foreign keys that reference each other. I have created a few tables using the "Create Table" function within Toad. Once I begin to add tables that require foreign keys I cannot find the tables listed in the drop down menu list of tables to reference. I only see one table I have created and the rest are not found. The tables do show up in my schema browser. I have tried restarting the program, connecting and disconnecting as well as different table names. I would like to know what I could possibly be doing wrong and how to fix it.