Ran,
I have some questions regarding your issue:
1. which version of UniFlash are you using
2. can you flash the device successfully through the GUI
3. have you ever get it to work before in your environment/setup
4. what is the exact command line you are using to load your program
If you can't get it to work through the GUI, please recreate the problem and obtain a log for us to debug. Please send the log and the binary you are trying to load to me at v-yang@ti.com
A guide to enable the DS log can be found here http://processors.wiki.ti.com/index.php/Troubleshooting_CCSv5#Debug_Server_Logging
Victor