Random behavior

I'm using Ad Campaigns in two blocks of the Omega template, one of them in Panels config. The ads show up in a random fashion, sometimes they show up, sometimes they don't. With <?php print_r($ads) ?> I get two outputs; when ads show up it's

Array ( [0] => Array ( [type] => flash [url] => http://test.europost.bg/?q=simpleads/redirect/223 [destination_url] => http://telish.bg/ [target] => 1 [image] => [image_uri] => [alt] => [nid] => 223 [node] => stdClass Object ( [vid] => 223 [uid] => 1 [title] => Telish wide [log] => [status] => 1 [comment] => 1 [promote] => 0 [sticky] => 0 [ds_switch] => [nid] => 223 [type] => simpleads [language] => und [created] => 1350550454 [changed] => 1350551189 [tnid] => 0 [translate] => 0 [revision_timestamp] => 1350551189 [revision_uid] => 1 [field_ad_type] => Array ( [und] => Array ( [0] => Array ( [value] => flash ) ) ) [field_ad_image] => Array ( ) [field_ad_flash] => Array ( [und] => Array ( [0] => Array ( [fid] => 372 [display] => 1 [description] => [uid] => 1 [filename] => 620x80.swf [uri] => public://field/flash/620x80.swf [filemime] => application/x-shockwave-flash [filesize] => 100732 [status] => 1 [timestamp] => 1350550454 [type] => application [rdf_mapping] => Array ( ) ) ) ) [field_ad_text] => Array ( ) [field_ad_url] => Array ( [und] => Array ( [0] => Array ( [value] => http://telish.bg/ [format] => [safe_value] => http://telish.bg/ ) ) ) [field_ad_url_taget] => Array ( [und] => Array ( [0] => Array ( [value] => 1 ) ) ) [field_ad_category] => Array ( [und] => Array ( [0] => Array ( [tid] => 13 ) ) ) [field_ad_start_date] => Array ( [und] => Array ( [0] => Array ( [value] => 10/18/2012 11:54 am [format] => [safe_value] => 10/18/2012 11:54 am ) ) ) [field_ad_end_date] => Array ( [und] => Array ( [0] => Array ( [value] => 11/18/2012 11:54 am [format] => [safe_value] => 11/18/2012 11:54 am ) ) ) [field_ad_status] => Array ( [und] => Array ( [0] => Array ( [value] => 1 ) ) ) [field_adcamp_list] => Array ( [und] => Array ( [0] => Array ( [value] => 228 [format] => [safe_value] => 228 ) ) ) [rdf_mapping] => Array ( [rdftype] => Array ( [0] => sioc:Item [1] => foaf:Document ) [title] => Array ( [predicates] => Array ( [0] => dc:title ) ) [created] => Array ( [predicates] => Array ( [0] => dc:date [1] => dc:created ) [datatype] => xsd:dateTime [callback] => date_iso8601 ) [changed] => Array ( [predicates] => Array ( [0] => dc:modified ) [datatype] => xsd:dateTime [callback] => date_iso8601 ) [body] => Array ( [predicates] => Array ( [0] => content:encoded ) ) [uid] => Array ( [predicates] => Array ( [0] => sioc:has_creator ) [type] => rel ) [name] => Array ( [predicates] => Array ( [0] => foaf:name ) ) [comment_count] => Array ( [predicates] => Array ( [0] => sioc:num_replies ) [datatype] => xsd:integer ) [last_activity] => Array ( [predicates] => Array ( [0] => sioc:last_activity_date ) [datatype] => xsd:dateTime [callback] => date_iso8601 ) ) [cid] => 0 [last_comment_timestamp] => 1350550454 [last_comment_name] => [last_comment_uid] => 1 [comment_count] => 0 [name] => koko [picture] => 0 [data] => b:0; ) [text] => [text_format] => plain_text [flash] => http://test.europost.bg/sites/default/files/field/flash/620x80.swf ) )

and when they don't it's just

Array ( )

I didn't have any problems until today, actually the random on/off started upon adding two campaigns on the front page.
I'm using the latest dev.
any ideas? thanks!