VixDiskLib_Read function not return

i use vddk 6.0 to backup virtual machine , and the vddk config file is:

tmpDir = "<tempdirectoryforlogging>"

vixDiskLib.transport.LogLevel = "6"

vixDiskLib.disklib.EnableCache = "0"

vixDiskLib.nfc.AcceptTimeoutMs = "180000"

vixDiskLib.nfc.RequestTimeoutMs = "180000"

vixDiskLib.nfc.ReadTimeoutMs = "60000"

vixDiskLib.nfc.WriteTimeoutMs = "60000"

vixDiskLib.nfc.TimeoutMs = "180000"

vixDiskLib.nfcFssrvrWrite.TimeoutMs = "180000"

vixDiskLib.nfc.LogLevel = "1"

but ,i fine the thread hang on VixDiskLib_Read all the time, not return for a long time， it is like the parameters in the config file are not become effective.

I hope some people can help me， thanks vrey much