我正在尝试运行负负二项式混合效应模型，但是R给了我这个错误：
while出错（iter
model<-mixed_model(total_taiwan_related_bill~log_district_total_export_to_China.hundred.million.+
log_chinese_investment.hundred.million.+
log_total_co_sponsor+
party_code+
nominate_dim1+
year_in_congress+
foreign_affairs_committee+
previous_Taiwan_bill,
random = ~1|state_abbrev,
family = hurdle.negative.binomial(),
zi_fixed = ~foreign_affairs_committee,data=data1)
谁能解释为什么会这样？预先感谢！