Hi Perumal,

Are there any other cell lines growing in the same incubator? How do they "feel"?

Vero cells are very "strong" and fast growing. The conditions you use seem to be suitable for these cells. Try to replace your growth medium with fresh one.

Yes, B95 cell line also am using. Growth of B95 was good in RPMI medium

we used to grow vero in dmem medium. The color of the media was dark pink. 

 If there's nothing wrong with the incubator then something is probably wrong with the growth medium or the cells.

Try to thaw a new vial and prepare new medium with 10%FCS, NEAA and anitbiotics.