[Koha] Error when checking and checkout books

[Vikas Salunkhe]

Dear all
when i try to checking  and checkout item following error is coming

Can't use an undefined value as an ARRAY reference at
/home/koha/lib/C4/ItemCirculationAlertPreference.pm line 263.

 For help, please send mail to the webmaster (webmaster at localhost), giving
this error message and the time and date of the error.


Please guide me

Vikas Salunkhe