This morning during the press conference for the Soyuz docking Bill Gerstenmaier NASA’s Associate Administrator for Space Operations confirmed that SpaceX had provided them with the final Dragon Spacecraft software which will be used for orbital operations. NASA are now reviewing the software and Bill estimated that they should be able to set an actual launch date for the next demo mission in about a month.
The reason the test has been delayed several times is because NASA, the Russian Space Agency, SpaceX and the other partners need to be 100% sure that Dragon will not pose any problems to the Space Station when it approaches. As with any project these things can take time and it is better to delay the test and be sure everything is working as needed than rush it and end up causing bigger problems.
NASA made sure that they wouldn’t need to rush the Commercial Resupply Services (CSR) by taking up over a years worth of supplies on the last shuttle launch.