The pipe should be smooth.
Put the capnut onto the tube, followed by the olive. Then slide the external-threaded stop end over the pipe and tighten with one spanner steady on the stop end, and one doing the capnut up. The olive will deform and grip the tube.
If it leaks, tighten it a bit more. If it still leaks, dismantle the joint. The olive should still grip the pipe and the capnut will be retained. Put a couple of wraps of ptfe, round the olive not the thread. Put it all back together and nip it tight, all should be well.
Put the capnut onto the tube, followed by the olive. Then slide the external-threaded stop end over the pipe and tighten with one spanner steady on the stop end, and one doing the capnut up. The olive will deform and grip the tube.
If it leaks, tighten it a bit more. If it still leaks, dismantle the joint. The olive should still grip the pipe and the capnut will be retained. Put a couple of wraps of ptfe, round the olive not the thread. Put it all back together and nip it tight, all should be well.