Strange line problem warning. Some help please.

Hello from Brazil again, Noda.

How is it going?
Im an old Aegaeus Theme and i love it. Im writing today coz i have one problem andi really dont know what could be.
Today these messege appears on my painel
Notice: Undefined index: hb_flex_slider in / (please find the full line in a next private msg)
I try to find some help on google but this hb-flex-slider thing so i decide to write to you again.
Can you help me? I really dont know what is that. The website is working, very fine, no problem around, but in my panel appears these.

I uninstall the theme and install again. but still there.

Please let me know. Thank you very much.

Have a great day.

Best Regards.

Erico.