求助各位大神，一作图他就提示r198 it‘s not a twoway plot type怎么办？

code 如下
twoway (connected m_employmentrate year2 if graphobs == 1 & T==1, m(O) lc(navy) mc(navy)) ///

>            (connected m_employmentrate year2 if graphobs == 1 & T==0, m(Th) lc(maroon) mc(maroon)) ///

>            , legend(order(1 2) cols(1) label(1 "UOS") label(2 "Mean of Other Universities")) ///

>                 xline(2011.5) ytitle("employmentrate") xtitle("Year") graphregion(fcolor(white))