Hi,
first of all, are you developing on Android, iOS or WindowsPhone?
Can you please give us more information about the crash? It happens with all your pdfs? Can you give us one of these to test it?
For Android you can find all the examples you need in the main demo project, check PDFReaderAct and PDFReader, regarding the thumbnails i suggest you to look at PDFThumbView (ViewLib --> com.radaee.util).
For more info you can check
the documentation
or
the knowledge base
.