1. Language communication problem: the message was sent in Chinese, but the recipient of the foreign optical shop was not proficient in Chinese, or the translation tool that the clerk was using could not accurately translate the message into language, which led to the inability to understand the message and thus unable to reply.
2. Time difference: the recipients of foreign optical shops work or live in different time zones, and the sending time is not the normal working hours or rest hours of the clerk, which leads to the clerk's failure to reply to the information in time.