I just tried to use "Update alignment" under DS 2.1 to import an .aln alignment file I got from Clustal W2. I got the following error message (I've edited out the full path):

Unable to find a unique importer for ~/clustalw2-20090317-09335920.aln. There are 2 matching importers:
Model: SDM - Format: CALN
Model: SDM - Format: QALN

What does this mean, and how do I get around the problem?

Thanks!