WC 7125 DADF wont recognize paper format

Hey,

  If i want to make a copy (A4) via DADF, printer displays following message:" Auto select is unaviable. Select a paper tray or load the following paper A4" The issue is only if I use Tray 1 - no differences is there A3 or A4 paper. All settings are checked and should be ok.

Any ideas?

Greetings,

Kawai