各位大神帮帮忙，我用R做plspm，outer model出错选择未定义的列，下面是程序，我该怎么办
OUTER MODEL
Error in `[.data.frame`(x$outer_model, tmp == i, 3:6) : 选择了未定义的列
a<-read.csv("diy.csv",header=T)
yxx<-c(0,0,0,0,0)
kkx<-c(1,0,0,0,0)
yqx<-c(0,1,0,0,0)
bzx<-c(0,1,1,0,0)
xyx<-c(0,0,1,1,0)
a.path<-rbind(yxx,kkx,yqx,bzx,xyx)
a.blocks<-list(1:6,7:13,14:18,19:21,22:26)
a.modes=rep("A",5)
library(plspm)
attach(a)
a.pls=plspm.fit(a,a.path,a.blocks,a.modes,scheme="factor",scaled=FALSE)
summary(a.pls)
plot(a.pls)