Eroare de instalare

Incercand sa instalez o noua tema, am afectat o anume setare si primesc acest mesaj:

Warning:+Creating+default+object+from+empty+value+in+/home/myname/public_html/wp-content/plugins/revslider/inc_php/framework/update.class.php+on+line+35

Warning:+Cannot+modify+header+information+-+headers+already+sent+by+(output+started+at+/home/myname/public_html/wp-content/plugins/revslider/inc_php/framework/update.class.php:35)+in+/home/myname/public_html/wp-includes/pluggable.php+on+line+1121

Nu inteleg ce am gresit si, astfel, nu pot indrepta acest lucru.
As aprecia un sfat care m-ar putea ajuta sa indepartez eroarea.

Cu multumire,