LTR_TNEW_CUSTOM_FORM tables

Suggestions on using TNEW tables LTR_TNEW_CUSTOM_FORM_DATA and LTR_TNEW_CUSTOM_FORM_SAVE_DATA

Our Valet manager has asked that patrons indicate the size of their vehicle when purchasing valet services.

In LTR_TNEW_CUSTOM_FORM_DATA we created a record with these values:
Organization  = Tessitura Web
Intended Use = KW:TN_Express_AUX:Valet Parking (selected from the drop-down)
Field Type = Dropdown    (we also tried Radio)
Is Required = checked
Field Name = Vehicle_Type   (no tickmarks around the field name)
Option Value = compact,fullsize,truck  (no spaces and no tickmarks)
Value Type = String

In LTR_TNEW_CUSTOM_FORM_SAVE_DATA we created a record with these values:
Organization  = Tessitura Web
Intended Use = KW:TN_Express_AUX:Valet Parking (selected from the drop-down)
Procedure Name = LP_VALET_VEHICLE_TYPE The stored procedure was added to TR_LOCAL_PROCEDURE
Use Stored Proc = checked
 other fields (CSI related) are blank

The (very simple) stored procedure LP_VALET_VEHICLE_TYPE:

INSERT LT_VALET_VEHICLE
VALUES (@Vehicle_Type)  

The stored procedure parameter @Vehicle_Type matches the Field Name value in LTR_TNEW_CUSTOM_FORM_DATA.
@Vehicle_Type is the only parameter for the stored procedure.

The table LT_VALET_VEHICLE has one column:  Vehicle_Type

Impusers (and others) has EXECUTE rights to the stored procedure.
Impusers (and others) has SELECT, INSERT rights to the table.

We may desire other values, such as order number and/or customer_number/customer_name.
However, for our testing we only passed through the vehicle type.

The stored procedure works in SMSS; the table LT_VEHICLE_TYPE is updated.

On the web, when prompted for Valet, the values compact,fullsize,truck are available and the web functions as expected.
I had a SQL trace running while I used the web, but I couldn't find anything in the trace results.
I'm not certain how to determine if the stored procedure LP_VALET_VEHICLE is called by the web.
I do know the table LT_VALET_VEHICLE is not updated.

I reviewed documentation and tried various combinations, but I can't get this to work.
... suspect I've missed something simple, and hoping someone can provide a little guidance.

Many Thanks
Wendell Baskin
Bass Hall - Fort Worth