Your chromosome names are using the Ensembl identifiers. UCSC requires their own chromsome names to be used, which look like "chr1". You can convert the Ensembl ones to UCSC just by adding "chr" to the front, which works for all the main chromosome scaffolds. The unplaced/unlocalized ones aren't as easy, but depending on your species and your analysis, might not be important. I think the mitochondrial genome is named MT in Ensembl and chrM in UCSC. You might also need to put a UCSC track header on the file indicating the type is narrowPeak, e.g.:
track type=narrowPeak name="Track name" description="Track description"