Windows CMAKE build failing

I compiled IlmBase with Cmake with no problems.  However, compiling the 
OpenEXR library has shown a problem.  When run, the b44 and dwa tables 
are not created and I get an error.

5>------ Build started: Project: IlmImf, Configuration: Release x64 ------
5>  Generating b44ExpLogTable.h
5>C:\Program Files 
(x86)\MSBuild\Microsoft.Cpp\v4.0\Microsoft.CppCommon.targets(151,5): 
error MSB6006: "cmd.exe" exited with code -1073741515

The same error happens if I use the NMake Makefiles generator of cmake 
(which is my preferred way of working).

The problem seems to be the line in the custom build step:

$(Configuration)\b44ExpLogTable > 
F:/code/lib/openexr-git/OpenEXR/IlmImf/b44ExpLogTable.h

It is not clear to me that $(Configuration) points to the actual executable.