[Protein-crystallography] HELP

[Peng Hao]

Dear All

I got a real trouble!!!

I have read the message 'how to convert CNS density modified file to mtz
forarp/warp' from forum of ccp4, it is quite useful, and now I have
successfully convert .hkl to .mtz. (the method I used is SAD)

But when I do auto-build in the ARP, I got trouble! 

in the ARP, there are 4 labels: 'Fobs, Sigma, PHIB, FOM'. 
But in my .mtz file I cannt find 'Sigma', and when I run the program, I was
told that the label of 'Sigma' should be added. So could you tell me what
should I do and where I can find 'Sigma'?

Thank you very much!!!

Best
Hao