error message for Draculas Shroud

[Samiam]

Hello,

I get an error message

no suitable method to override.

This is for the first line in the text below.

public override void OnRemoved( Object o)
{
if( o is Mobile )
{
( (Mobile)o).RemoveStatMod( "MOD0" );
( (Mobile)o).RemoveStatMod( "MOD1" );
( (Mobile)o).RemoveStatMod( "MOD2" );

}
if( o is Mobile && ((Mobile)o).Kills >= 5)
{
( (Mobile)o).Criminal = true;
}
if( o is Mobile && ((Mobile)o).GuildTitle != null )
{
( (Mobile)o).DisplayGuildTitle = true;
}

base.OnRemoved( o );
}

Thanks ahead of time for the help