InDesign styles may be grouped or ungrouped. Grouped styles require a specific syntax.

For ungrouped styles, the value specified in the elem2styleMap.xsl templates is just the style name as it appears in the InDesign style list, e.g. "Body Text" or "LI Bullet 1" or whatever.

For grouped styles, the value is the group name, a colon, and the style name, e.g. "Chapter:Chapter Title", where "Chapter" is the group name and "Chapter Title" is the style name within the group.