[Chimera-users] Sec structure loss

Hi, I'm seing something strange with secondary structure assignments in peptides. Two examples: PDB 1axc has a peptide bound to PCNA with beta strand interactions and chimera doesn't pick it up as a strand. In the other example, 1rxz, it picks up the strand in a similar peptide but the strand disappear when I run matchmaker with 1ul1 (which also has a strand at the c-terminus that is not picked up. Is there any explanation? Are the criteria for secondary structure assignments to strict? One more thing that may have been asked already!! how does one keeps the NH and CO of the peptide bond displayed in the ribbons view? Thanks James