各位SAS 大大，我在用Fama Macbeth 的宏跑回归，但是一直报错。不太清楚到底哪一步有问题，求大大们点拨指导一下~

多谢多谢~

%let firm = l_lnasset l_mlev l_fcf l_rnd salesgrowth firmage;
%let board = logsize duality female_dir outsidedir;
%let ind = i1-i47;
%let year = y2000-y2009;

%regby(dset=z6,byvar=fyear,yvar=tobinq,xvars=founder &firm &board,minobs=0,print_est=yes,
print_r2=yes,indformat=);

ERROR: No valid observations are found.