请教加拿大移民问题。

我申请移民有一段时间了。前一阵子给buffalo发信。回信两次都是这个

We have requested background information from other government offices(s). Unfortunately, we cannot respond to requests for the status of your application before this information is received.

请问他们在查什么，听说几千人里才5－6个查background.我不会是中了吧？如果中了，通过几率有多少呢？thanks