finding lincRNA alignments with BLAST versus BLAT

Hello,

I have a lincRNA sequence (XLOC) that I retrieved from the Broad Institute. When I BLAT the sequence against the human genome, I get a 100% match and it aligns with the correlating transcript (TCONS). However, when I BLAST the alignment, I get "No significant similarity found". Can anyone suggest why this might be?

Thanks.