Severe Bug - App ist fehlerhaft

The App. has a severe bug. I was sending a document from free iDo to the senior version as I wanted to migrate my existing documents. However, Senior iDo does not allow me to Open this doc, nor can I open any of the other docs which I created in Senior iDo meanwhile.

Viktoria S.69 about iDo Notepad Pro (Journal/Diary), v2.51