Board train in a different station from ticket

I'm interested in buying tickets from Pingyao to Beijing, high speed type, but it appears to be unavailable. However, the same ride departing from Yongji is available. If I buy the ticket from Yongji, would it be a problem if I try to board at Pingyao Station at 13:40, when the ticket is showing 11:29 departing time at Yongji?