stata随机森林循环 把in视为变量了

在这一句中，系统好像把in视为变量了，怎么处理呀：rforest default_payment_next_month limit_bal sex education marriage_enum* age pay* bill* in 1/1500, type(class) iter(`i') numvars(1)

gen out_of_bag_error1= .
gen validation_error= .
gen iter1= .
local j=0
forvalues i=10(5)500{
    local j=`j'+1
    rforest default_payment_next_month limit_bal sex education marriage_enum* age pay* bill* in 1/1500, type(class) iter(`i') numvars(1)
    qui replace iter1=`i' in `j'
    qui replace out_of_bag_error1=`e(OOB_ERROR)' in `j'
    predict p in 1501/3000
    qui replace validation_error =`e(error_rate)' in `j'
    drop p
}

in not found
r(111);