问题如题，求各位大佬帮忙解答下
if `ii' == 1 {
disp "*** Dynamic Panel FE with a threshold ****"
xtreg y y1_1 y1_2 $ind_1  $ind_2, fe robust  //运行完该语句显示=exp not allowed
estadd scalar threshold = gamma
estimates store FE
test lr_1 = lr_2