Hi Kim,
Glad I was able to help. It is a little weird but this happens if you have created some new expense types and missed the step to add them to table T706S_RECEIPT.
It is used for restricting particular expenses types for a schema (only if you are using multiple schemas) but if you are only using ONE schema then I would not expect any entries in this table. So basically even if you delete all the expenses types from this table then all your expense types will still show in the drop down list. I am not suggesting doing this especially for your huge list of expense types.
Also if you think that the above response was right then please can I request you to mark it as correct so others in this community can benefit if they face a similar issue 
Cheers
Ankur