Help with creating seamless tile

[iamtheblues]

I thought I had nailed the principles of creating seamless repeating tiles, but apparently not.
Attached is the result I've ended up with after endless hours of trying to create a perfect seamless tile.
I have also attached the .xar file which contains the original vector I made, which was my attempt at creating an Escher style pattern.
Any help on this would be very much appreciated.