Most crimps, esp the barrel type you have, need the wires twisted first, then slide the crimp into place ,and crimp with the proper tool.
I added a webpage that shows a couple of splices.
http://www.tpub.com/content/construc.../14027_122.htm
Here is another connection method ,
http://multimedia.mmm.com/mws/mediaw...666UgVCOrrrrQ-
UL has in the last few years require that all crimping be done with a tool that has two indenting dimples. Your tool is probably the older version .
The actual crimp you use must be rated for direct burial, and I do not believe the barrel crimps you want to use are rated as such. You may want to look at using somethng simialr to the second product I offered.