Proper way to say "I don't know what the problem is." What is the proper way to say "I don't know what the problem is" in Mandarin?
Not sure if this is a “问题” or a "关系“ structure.
Paraphrase as 'Dunno where the problem lies, (but it won't start.)'  

我（也）不知道问题出在哪里,（但是它启动不了。）