求助各位朋友，PVAR命令运行后显示↓是怎么回事？应该如何解决呢？
pvar h_lnselfseller2 h_lnselfupdate2 h_lnavgprice2 h_lnnongrowthrate2

derivative already defined for parameter h_lnnongrowthrate2___0000 in equation 4
r(498);