p estimates of 1.0

[tpinn]

Hello,
I have a few models with very large standard errors for p1... this seems to be related to the estimate for p, which is 1.0 (constant p). But I do not know why it should be so high (species are not detected in every interval when present at a site). Does anyone know what conditions would give p1 estimates of 1.0?

Thanks!
Tracy