求助:我用它作图时打出现下面的问题:请各位高手多多帮忙,十分感谢.

input time y1 sd1 y2 sd2

time y1 sd1 y2 sd2 1. 0 11.8 1.4 10.6 1.5 2. 2 18.5 2.3 16.3 2 3. 4 25 3.4 18.9 2.1 4. 6 27.3 2.9 22.6 1.9 5. 8 30.4 3.2 22.8 1.8 6. 10 31.7 3.4 22.6 2.3 7. 12 32.5 3.5 22.9 2.2 8. end

.. save d:ex.dta file d:ex.dta saved

. br

. graph y1 y2 time, c(11[-]) s(ot) xlab(0(2)12) ylab y1graph_g.new (y2 time, c(11[-]) s(ot) ylab), xlab(0(2)12): class member function not found

y1 is not a valid graph subcommand