mount ok,but show: I/O error ,why?!

sgs

now,on my renee i can mount sgs :/test to renee:/uptest \r\nbut when : \r\nrenee#ls /uptest \r\nshow me: /uptest : I/O error? \r\nwhy? \r\ni try it many times ,get the same result \r\n:/uptest :I/O error \r\n\r\n(ping sgs 129.9.1.1 or ping renee 129.9.1.2 are ok) \r\n(/uptest can be read or write)