望哪位大神指导一下，在进行Adaptive kernel与Fixed kernel画图进行比较时，运行到graph fixed adaptive x, xlab ylab c(ll) s(dS)这里时，显示出错误。程序如下：
. webuse trocolen.dta
. kdensity length, nogr gen(x fixed)
. akdensity length, nogr gen(adaptive) at(x)
. label var fixed "Fixed kernel"
. label var adaptive "Adaptive kernel"
. graph fixed adaptive x, xlab ylab c(ll) s(dS)
    fixedgraph_g.new adaptive x, xlab ylab c(ll) s(dS): class member function not
    found
r(4023);