[Chimera-users] Concerns regarding secondary structure

I have some concerns with Chimera's secondary structure detection/depiction. I am using Modeller to predict some 3D structures. I open my predicted structure in pdb file in Chimera along with the original structure I based my prediction on, and find that my predicted structure lacks two beta sheets that the model protein has, though the AA that compose the B-sheet are identical for the two proteins when I compare sequences with Matchmaker. I tried opening my predicted structure in MolMol and it detects the B-sheet, though I hugely prefer Chimera, so if you could solve this problem for me I would be very greatful. Thanks in advance, and regards Rodrigo Quiroga