Problem using inprod() to summarise linear predictor - openbugs

Question

I am having a problem when trying to summarise my aditive predictor:
mu[j] <- b0 + weights1[1] * A[j] + weights1[2] * A[j+1] + weights1[3] * A[j+2] + weights1[4] * A[j+3] +
weights1[5] * A[j+4] + weights1[6] * A[j+5] + weights1[7] * A[j+6] + weights1[8] * A[j+7] +
weights1[9] * A[j+8] + weights1[10] * A[j+9] + weights1[11] * A[j+10] + weights1[12] * A[j+11] +
weights2[1] * B[j] + weights2[2] * B[j+1] + weights2[3] * B[j+2] + weights2[4] * B[j+3] +
weights2[5] * B[j+4] + weights2[6] * B[j+5] + weights2[7] * B[j+6] + weights2[8] * B[j+7] +
weights2[9] * B[j+8] + weights2[10] * B[j+9] + weights2[11] * B[j+10] + weights2[12] * B[j+11]
by using inprod(). This is what I thought should be the equivalent:
mu[j] <- b0 + inprod(weights1[],A[j:(j+11)]) + inprod(weights2[],B[j:(j+11)])
While the model compiles and seems to work, it stays updating forever. Its been running for hours and it does not end while the first approach ends in few minutes.
These are the priors, just in case:
weights1[1] ~ dnorm(0,1.0E-6)
weights2[1] ~ dnorm(0,1.0E-6)
for(t in 2:12) {
weights1[t]~dnorm(weights1[t-1],tauweight1)}
for(t in 2:12) {
weights2[t]~dnorm(weights2[t-1],tauweight2)}
b0 ~ dnorm(0,.001)
tau ~ dgamma(0.001, 0.001)
sigma <- 1/sqrt(tau)
tauweight1~dgamma(1.0E-3,1.0E-3)
tauweight2~dgamma(1.0E-3,1.0E-3)
I am calling OpenBUGS from R using R2OpenBUGS just in case.
Thanks very much for your time!