OpenBUGS软件设置初始值的问题

我有一个OpenBUGS软件设置初始值的问题请教。恳请回复指点！

代码如下：

#Model

model {

# Likelihood

for (i in 1 : N) {

Y[i] ~ dpois(mu[i])

log(mu[i]) <- log(e[i]) + b + S[i]+u

# Area-specific relative risk (for maps)

RR[i] <- exp(b+S[i]+u) 

}

# CAR prior distribution for random effects:

S[1:N] ~ car.normal(adj[], weights[], num[], tau)

for(k in 1:sumNumNeigh) {

weights[k] <- 1

}

# Other priors:

b ~ dflat() 

beita1 ~ dflat()

u~dnorm(0,x)

x<-a*a

a~dunif(0,100)

tau ~ dgamma(0.5, 0.0005)  # prior on precision

sigma <- sqrt(1 / tau) # standard deviation

  S.mean <- sum(S[])

}

#Data

list(N = 16, 

Y  = c(  12597,   11327,   4396,   10175,  4938, 2368, 4940, 4715, 5186,8751, 6759, 2228, 6726, 2442, 1059, 737),

e  = c(  109, 99, 38, 89, 42, 21, 43, 41, 44, 76, 

        59, 19, 57, 21, 9, 7),

num = c(4, 4, 4, 1, 4, 4, 6, 3, 5, 5, 2, 1,

        6, 1, 4, 2),

adj = c(

10,9,3,2,

11,10,4,2,

10,9,7,1,

2,

15,14,13,8,

16,15,13,9,

13,12,10,9,8,3,

13,7,5,

13,7,6,3,1,

11,7,3,2,1,

10,2,

7,

15,9,8,7,6,5,

5,

16,13,6,5,

15,6),

sumNumNeigh = 56)

#Inits

list(tau = 1, b = 0, beita1 = 0,u=0,S=c(0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0))

出现错误为：