Don't worry, the iPad is probably still charging, but it isn't getting enough juice to display the lightning bolt that indicates it is charging.
Echegbula onwe gị, ọ bụrụ na iPad ka na-ebugharị, ma ọ bụghị inweta ihe ọṅụṅụ zuru ezu iji gosipụta ugodi nke na-egosi na ọ na-akwụ ụgwọ.