Style sometime working and sometime not working in jasper

Sometimes style is working and sometime it is not working in jasper to make any data/text bold.What could be the possible reason.

This is to confirm that <style isBold="true">Radhika Ghai</style> with Employee Code <style isBold="true"> C002</style> is working with Clues Network Private Limited in the capacity of <style isBold="true">CBO & Co-Founder</style>.

sometime above text is coming correct with specific text bold.