Scripting Automation Sometime works sometime fails

I hope someone can help me. I have a script that sometime will work fine for days and then it will suddenly stop working. Based on the log (see below) it has a connection issue. When I run the Commander interface the same connection works fine every time. I have provide the script I call and the last part of the log file that appears to show the connection issue. If more of the log file is needed, it can be provided.

Script:

option batch abort
option confirm off
open sftp://UserName:Password@somesite.com/
put C:\ClientProjects\ClientName\FTP_Files_To\*.to /ClientName_TO_2016/
exit


Log:

. 2016-03-29 23:01:05.836 Looking up host "somesite.com"
. 2016-03-29 23:01:06.028 Connecting to xxx.xxx.xxx.46 port 22
. 2016-03-29 23:01:06.057 Server version: SSH-2.0-2.0
. 2016-03-29 23:01:06.057 Using SSH protocol version 2
. 2016-03-29 23:01:06.057 We claim version: SSH-2.0-WinSCP_release_5.6.3
. 2016-03-29 23:01:06.070 Using Diffie-Hellman with standard group "group14"
. 2016-03-29 23:01:06.070 Doing Diffie-Hellman key exchange with hash SHA-1
. 2016-03-29 23:01:06.471 Verifying host key dss 0xbdfc26f03b9fd6ca 1482d29a5ba9be33 17d828928dd57af8 96543b6ae1dde7d1 e16cf0bc30cc7202 d107c397f8adab90 04ea4f20f95b71f5 bd07b312be3e14de 0cadd30681fae3c5 657b544edfcfca25 29a809db66915527 0b7f109dadb1a9a3 fe56661389a703ff 7adb0ecb7969e0c3 a536534ce7c4ce2f 601d160863c59460 4c3b859200c4802e b14ab6392cc52d64 e7367cac05d3cf0c 842410eebe82a4d2 7dcaab89c35b6207 f5db8689995db3a5 3e69cd38a4dee013 e79389be14f8cd3b 19c97fe0bc16f5bd fa01900d2fb14db8 075b563e1686610a d0d487ae26b277da e64a9d243bb462f3 80d7c0c2a956df9e e2c84bfc56ce4495 5624dfc4aeb1596b ,0xdd0d37d51148e0e1 b5d44cd28481db7d 426fe5e3,0x7f406750869f47f3 d20033b1927132ac c7bd748bdda4db61 a2a962433f8e8ccf 51c5e173c1e239cb 46fbf7668921f23d f70461177bd19747 aeec02b9b47bf9a7 5ba9808883a2a8f9 f32162f4178e82ab 549d98bc8b7e0437 6c15b1ad150d8954 afff51d526c18592 049a65fb1c8b7266 8b60616624f7db99 7d631110b44286a3 c707355809f1f7d1 6ae089f91d9679a4 a1b65b0693328422 85c5878b6906cd53 06a8fc63f68a214a 73de3f89d627178d 1af417913255ad1d d0b5cd49b5df5e45 168103cc52c09182 ee693e0671481624 d264843c5c6d85cc a28a5a11a4216510 062f2cdd3497e16e 3a9fd4f142dff7f1 7fe0ac9051dad7ac 2bcb3b57371f502a ,0x66f676ee2e02d378 d78a6b0912ca6e95 702f98b878eb7db5 284ee969b97f4a33 86e34cd7b123ceaa ae653161c2615060 4aef7d8ce7124179 9b5e5e550fa97b67 f79523d42475bfd3 e17c6ab9c8097fd6 1fa045e43d8a807d 339d65ad226b58d6 fc2badc3bdabd8d6 c2e48c26b8e71216 960e4ac8a7c3a85a 876439a77af26750 1d6c329f4798adcd d98570c78a810cf0 415aae7c83f38d1e 50feda337f71621f 8ccddd76d68fee73 06a0dc323706d044 095c8a0f28afc625 33ce1a25e6c07351 f91f5a7194a33187 999b0209776c3ebc 07174fc450d157ea 8241fac1a07dd9a9 16d7ac779f0cc0cf b2163a242c71e280 39e8468419b979b4 f924f92082d4684 with fingerprint ssh-dss 2048 2f:76:0b:f0:71:6c:26:af:87:b9:31:fb:10:a1:ef:78
. 2016-03-29 23:01:06.473 Asking user:
. 2016-03-29 23:01:06.473 **Continue connecting to an unknown server and add its host key to a cache?**
. 2016-03-29 23:01:06.473
. 2016-03-29 23:01:06.473 The server's host key was not found in the cache. You have no guarantee that the server is the computer you think it is.
. 2016-03-29 23:01:06.473
. 2016-03-29 23:01:06.473 The server's dss key fingerprint is:
. 2016-03-29 23:01:06.473 ssh-dss 2048 2f:76:0b:f0:71:6c:26:af:87:b9:31:fb:10:a1:ef:78
. 2016-03-29 23:01:06.473
. 2016-03-29 23:01:06.473 If you trust this host, press Yes. To connect without adding host key to the cache, press No. To abandon the connection press Cancel. ()
. 2016-03-29 23:01:06.473 Attempt to close connection due to fatal exception:
* 2016-03-29 23:01:06.473 Host key fingerprint is ssh-dss 2048 2f:76:0b:f0:71:6c:26:af:87:b9:31:fb:10:a1:ef:78.
* 2016-03-29 23:01:06.473 (Exception) **Host key wasn't verified!**
. 2016-03-29 23:01:06.473 Closing connection.
. 2016-03-29 23:01:06.473 Sending special code: 12

Thank you.

You are not verifying the server host key in the script.
https://winscp.net/eng/docs/scripting#hostkey

So I wonder how comes it works sometimes at all.
Please attach a complete session log file from both successful and failing session.

I currently don't have a copy of a successful connection. I didn't start the scripting process until just the other day after 4 failures in a row. My bad. But, my question is, why would it always connect via a manual terminal session using the Commander interface (that I have a script of) and not a scripted session?

Do you mean GUI session?

Most probably, you have the host key cached.

Again, see
https://winscp.net/eng/docs/scripting#hostkey

and also
https://winscp.net/eng/docs/ssh_verifying_the_host_key
https://winscp.net/eng/docs/faq_hostkey

I added the Host key to the script and it seems to have fixed the problem. I haven't had a failure since I added this. I really appreciate your help with this.

Yes, I was talking about the GUI.

Again, thank you for the help

Gary