在R中使用nls()与SSlogis()和prediction()的未知错误消息

I'm fitting a logistic model (self-starting; SSlogis) to data of multiple populations of birds using nls(). My goal is to fit an expected function to the data (using only part of each dataset) and display a measure of the variance about the expectation on a graph. I then want to fit and plot the observed function (using the entire dataset for each population) to determine if the observed dynamics fell within the variance of the expectation. Here's my code as currently written to accomplish this:I'm fitting a logistic model (self-starting; SS