Apps back button returns to wrong activity when opening pdf via uri

[geekyhawkes]

Im hoping this is simple, but im fairly confused as to what is going on. I am launching a PDF from an Imagebutton in an android activity using a piece of code I copied from elsewhere in my app.

if (v==imagebutton20) {

                File file = new File("/sdcard/documents/20.pdf");
                  if (file.exists()) {
                        Uri path = Uri.fromFile(file);
                        Intent intent = new Intent(Intent.ACTION_VIEW);
                        intent.setDataAndType(path, "application/pdf");
                        intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

                        try {
                            startActivity(intent);
                            overridePendingTransition(R.anim.zoom_enter, R.anim.zoom_exit);
                        } 
                        catch (ActivityNotFoundException e) {

                        }
                  }
            }   //end of   load

The pdf loads fine but when i press back the activity that launched the pdf isnt show, instead it returns to the activity before. I have tried commenting out the
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

but the same effect. What am i missing? Sorry but i couldnt make sense of the official android guide, must be having a thick day!