Error message from control app don't show up in build log

Hello,

I'm running FluentMigrator.Console as a part of the build process (MsBuild) with TeamCity and I'm getting this output in the build log (as seen on localhost:8080 on the build server):
(_Migrate target) ->

The invocation looks like this in the .build file:
<Exec Command="$(FluentMigratorPath)/Migrate.exe &quot;--target=$(BuildOutputPathBin)/XXXX.Data.Migrations.dll&quot;
    --db=sqlserver2005 &quot;--wd=$(BuildOutputPathBin)&quot; &quot;-c=$(MigrationDb)&quot; --verbose=true" />

And the code that generates that output looks like this:

line 1:   
catch (Exception ex)
{
    using (var message = new StringWriter())
    {
        message.WriteLine("An error occured executing the following sql: ");
        message.WriteLine(sql);
        message.WriteLine("The error was {0}", ex.Message);
    }
}

this is then written to System.Console.Error : TextWriter.

How do I get the output?