series rocv10=-4.89
series rolling=na
equation eqrolling
for !i=0 to 35
smpl 1956+!i 1972+!i
eqrolling.ls d(lngongye) lngongye(-1) d(lngongye(-1)) c @trend
rolling(!i+3)=eqrolling.@tstats(1)
next
smpl @all
graph graph2.line rolling rocv10
show graph2


为什么上面程序在运行时总是显示“no workfile exists--use new or open to creat or load a workfile. in "series rocv10=-4.89"”