what really went wrong with disha and tara?

i know they are not very good actresses but most of the current working actreseses aren't that great either? they are pretty good looking girls. what i find strange they don't even get flowerpot roles and supporting roles in any commercial films anymore. disha did a small role in kalki but there is no news of her next movies. disha started off well then fizzled out and tara made debut with dharma.