Uncouple every connection that you created and use a strong flashlight to check the flare surface and the matching shoulder. The flare should show a uniform shoulder width for the full circumference. Flush the caliper end out with CFC free brake cleaner and pressure air blow it dry. Check the threads on both halves of the connection to make sure they are clean and that it did not get crossthreaded somehow. Re-assemble the connection, get it as finger tight as possible and use a genuine flare nut wrench or crowfoot adapter with a johnson bar to make achieve the final tightness. Be aware that you are mating two sealing surfaces to each other that have not been "talking" to each other before and they will "work" on each other to some degree to get as physically tight a surface match as possible. Take a moment to recheck the hoses and make sure you put in the brass crush washer on either side of the banjo fitting before screwing in the bolt or it will leak.
Once you have visited all the connections having issues and made sure they are made well, and when you think you have them as tight as possible, then go back and lean on them again. You might be surprised at what you find. The last set of brake lines that I fabricated and installed took three subsequent passes with a flare line crowfoot wrench on a 3/8ths power bar to get to the "No Mo" point of tightness.
Nick