GMM started : 13:34:17  
accumulating matrices equation 1,2,3,calculating b2sls
unrecognized command:  diag
r(199);

end of do-file

r(199);

. ssc install diag
ssc install: "diag" not found at SSC, type -findit diag-
(To find all packages at SSC that start with d, type -ssc describe d-)
r(601);

. findit diag
请问怎么解决