It seems that you cannot inject the skill “hybrid weapon rigging” without first training “jury rigging” to level 3.
Of course I am aware you cannot begin to TRAIN the skill until reaching level 3, but you should be able to INJECT the skill so as to add it to the skill queue so it will train AFTER jury rigging has reached lvl 3 automatically.
Sorry if this has been previously reported. I did search but found nothing.
Edit: There is something up with this. It seems it does register but it does not appear in the skill queue perhaps until you restart the EVE client. Not sure, but something is definitely off. The skill book would just not inject, or seemed not to.