DS-5 FVP debugger always shows "Failed to load symbols for "Hello World.axf""

I started to use DS-5 recently and applied for a evaluation license for professional version.

I followed instructions strictly from this page DS-5 Documentation & Resources / Tutorials / Getting Started with ARM DS-5 | ARM DS-5 Development Studio

But I got this error message, like this picture shows

This make me can't debug from source-level.  I can't set breakpoint into c file , but i can set breakpoint into disassembly file. Is  there any solutions?