Dropper isnt dropping.

Guys i have a problem with my dropper which is not dropping items. Redstone is ok and even in my test world it works perfectly, but when i built it in my survival world this happend. When i place repeater directly into the dropper it will work but than it will break my machine so i placed repeater which is facing to block and next to the block is dropper. THen IT will stop working. Also if i destroy that dropper and replace it, it will drop 1 item and than it will stop working again. Same thing for the repeater (replacing). Also when i change the delay of the repeater it will start working but if i put it back to 0 delay it will stop working aGaiN..