Hi,
By default EasyDCP assumes that your material is in REC 709 (it uses a lut to convert to XYZ I think). You can bypass this conversion and use dpx files that are already in XYZ. In your case you should output the dpx files as they were going to the NEC projector from davinci, using the rgb to xyz 3D lut you used.
If your lab uses EasyDCP+ (a version with more features) you can render in RGB and then apply a 3D lut in the program settings to convert to XYZ, but in your case it´s easier to apply it Davinci.
There are demo versions of easyDCP creator and player available online, so if you keep having issues you can create a dcp and preview it using your projector.