Hello Damon,
You can use Fiddler to examine the content of the web page generated.
You can also use the SM50 trace (checking WEBGUI as active component) and ICM trace level (2 or 3) to verify the values that actually reach the server.
If the server receives the values for both fields, then it might be a problem within the application.
If you have a custom transaction code, you can test it via WEBGUI service and see whether it works.
I hope this helps.
Regards,
Cris