This is my personal experience, however I used some content from another post by "personalexperience" to help me explain, expecially the Chinese part (I can not type Chinese on this computer). I realised many people may have the same problem like what I had. The reason I borrow the post written in Chinese is because in this way this post can be retrievable by Chinese search engines like Baidu and I hope it would be helpful for the Chinese community.
CASE STUDY--I-94過期怎麽辦 ?
Laomo於2005年March獲得工作簽證身份（H-1B）身份，INS的 Final Approval Notice 的有效期（Expiration Date）是2008年February。
Laomo於2007年5月回國，然後從xxx機場入境，my visa, which was issued in Shanghai, expires on August 10th. 機場海關官員在A的I-94卡上寫了Expiration Date on Aug 10th, 2008. I did not realise this error and never paid attention to my I-94 until recently I did
my H1b extension.
由於Laomo將延長（Renewal）工作簽證身份（H-1B）身份。 才發現I-94卡的有效期（Expiration Date）2007年8月10日早已過期5個月，如何辦？
Solution:
I went to USCIS office, they said I overstayed and had been illegal in this country for 5 months. They said I had to leave this country ASAP. Thanks God they did not handcuff me and deport me on the site.
I realised, to the viewpoint from INS, this is a very serious problem. They will think you have been illegally overstayed for more than 5 months. If I leave US now, I will make it a fact that I have overstayed in this country and illegally worked for 5 months.
After Laomo consulted different attorneys, they all say, do not leave US and solve it locally. One lawyer told me that I have to clean up this mess before I leave this country otherwise I would have difficulty comming back to this country again. I took his advice and decided to try my best to fix this error.
I searched online extensively and found 1 post that was really helpful. The case was similar to mine but the guy overstayed even longer, for 9 months. He had this error fixed at Customs and Border Protection - Deferred Inspections Office. I found this information extremely helpful. Because I realise that although CIS and CBP are both branches of DHS, they are different and my problem was caused by human error made by CBP officer. So based on the principle "Yuan You Tou, Zai You Zu", I should have better chance of having this error fixed if I go to the BCP office.
So I found the telephone number of Customs and Border Protection - Deferred Inspections office in my area. I called and the operator asked me to make an appointment with USCIS. I explained to her over the phone that I did go to USCIS last time and seemed like people there had problem understanding my problem. She said I should go to the USCIS office and asked to see a BCP officer.
So I did go there again and asked to see a BCP officer. The BCP officer obviously saw what had happened to my I-94 and after asking me several simple questions I was referred to Customs and Border Protection - Deferred Inspections office upstairs. There a lady checked my passport and documents and asked me to take a seat and wait. In about 15 min I got my new I-94 with the correct date that matches my I-797 document!
The lesson is to check you I-94 expiration date carefully. It has the priority to override your earlier documents.
