实在是不太明白，麻烦论坛的各位stata大神帮帮忙 看一下  命令哪里出现了错误
reshape long id name province type lnL cic lnY_added lnK age state lnI exit, i(id_in_panel) j(year)
tab year, gen(dum_yr)
drop dum_yr6
tab cic, gen(dum_cic)
drop dum_cic464
tab province, gen(dum_r)
drop dum_r31
tab state, gen(Dum_state)
global dummy "dum_yr* dum_cic* dum_r*"
opreg lnY_add, exit(exit) state(age lnK) proxy(lnI) free(lnL $dummy) cvars(Dum_state1 Dum_state2) vce(bootstrap, seed(1357) rep(5))
这是stata显示的出现错误的结果

(running opreg on estimation sample)
variable year2002 not found
an error occurred when bootstrap executed opreg
r(111);
我使用的是面板数据 实在不太明白哪里错了，谢谢谢谢