Plugin debugging missing download button

I have the following scenario

• Select Action
• Action chosen prompts to Add a new Letter Entity
  • I have a plugin that fires Pre-Operation on the Server on Create of the Letter Entity
    • The plugin has an error but the Business Error Screen does not display
    • The trace in the plugin do not show in the plugin trace log shows no entries for this plugin but other plugins traces show (so yes the trace logging is turned on)
    • I turned on the profiler in the Plugin Registration Tool
      • The following error shows - note no download button shows
        • Thoughts?  Why is there no file to download?
• Letter Entity Screen shows
• Save of the Letter updates the entity

Diane