I'm preparing smallRNA samples for v1.5 single end reads. After the cDNA library generation I've checked that the constructs contain each adaptor and an insert on a PAGE gel and see bands of the correct size (around 100nt). When I Sanger sequence(for final validation)however, I continually see the adaptors ligated together with no insert. I have cloned the into a plasmid and amplied the construct from here and the size still looks good. Has anybody else had a similiar problem? Does anybody have any suggestions.