stem opt extension 网上查不到状态是个什么情况

stem opt extension
I797 receipt，received date Jul.31，notice date Aug.03
YSC179028XXXX
到网站查询 egov.uscis.gov 今天查了一下还是
·My Case Status does not recognize the receipt number entered. Please check your receipt number and try again.·
有人见过这是个什么情况？四周了。