Why is the “Start Profiling” button and menu item disabled?
The profiling option works by actually executing your application and watching it to see what it loads. In order for this to be possible, you need to have opened an executable (usually has an EXE extension) rather than a DLL. If you want to profile a DLL, you will need to open some executable that loads the DLL (see the FAQ about using REGSVR32.EXE to load DLLs). The profiling feature also requires that the executable you have loaded is for the same CPU architecture as the version of Dependency Walker you are currently running. For example, you need the 32-bit x86 version of Dependency Walker to profile a 32-bit x86 executable, and the 64-bit x64 version of Dependency Walker to profile a 64-bit x64 executable.
