I work for a land trust in Canada and I am trying out zonation to use for nature preserve prioritization. I have been able to figure out how to use most of the features we need, however I can't seen to get the SSI files to work and there doesn't seem to be an example in the tutorial. I have the SSI feature list written as shows in the manual and the txt files for each species with the data (three columns the first with longitude, then latitude, then the pop size), but the error I get is "could not read file" for each of them. What could I be doing wrong?