I'm trying to migrate from building by Want to Rake (Want is an analog of Ant for building Delphi projects; It "understands" the same Ant's options, so I use a build step of type Ant)
I've added a build step of type Rake. In it's properties I've set "Build Properties" (pairs like <property>=<value>)
When this step is run it executes Ruby Rake (on a Windows node):
rake.bat -D<property1>=<value1> -D<property2>=<value2>.... blah-blah --rakefile <rakefile> <task1> <task2>...

but Ruby Rake does not "understand" such a notation of properties.
It handles notation
rake <property>=<value> ... --rakefile <rakefile> <tasks...>
(without -D switch)

P.S. Internally rake sets these defined properties to environment variables so we can partly "workaround" such a behaviour by setting Environment Variables, but conception is broken.
P.P.S Also, one could override Rake's behaviour with command line options but -D option is reserved by Rake:
rake --help
...
Options are ...
...
    -D, --describe [PATTERN] Describe the tasks (matching optional PATTERN), then exit.
...