Whenever I try to save the tree image using export image option of Splitstree 4, it is saving as *.aln file instead of *.png file. Wonder what I am missing? Any idea what's wrong?
On the export window, make sure to select the output file type. This can be the cause of why you end up with ALN instead of PNG. Alternatively, use the Save as function if you can't find PNG file type in the export window.
