Hi!
  Every character in my game has one Talent. The system to design Telents is easily customizable and is an analog system, you can use it to create stuff I never even thought of. There are very few restrictions, basically you can't use it to add to skill rolls or Ability scores (i.e., Strength).
  But all the players that have messed with it seem to be at a loss to come up with a Talent. I can't tell if it is because they haven't read my rulebook (they haven't) or because I am not inspiring them into being more creative.
  Am I worried about slackers or is this a design issue or..?

Do you give examples or guidelines?  If people are having trouble creating characters, you can solve a lot of problems by using descriptive examples and providing complete samples.  Explain why the talent system is there and how you are supposed to use it.  Sometimes you are just dealing with player's who aren't used to making something that is supported by the system.  Some people take a look at the spells in the D&D player's handbook and think that's all there is, others look and see it as a guideline to make your own spells.  Some people, still yet, don't like to create their own material, even if the system supports it.  If you provide a hefty amount of examples and guidelines (that lazy people can just pick up and use), and they still are at a loss, my money is on slackers.

What's the point of Talents if they never modify a roll? Explaining that to people generating characters might help. From your description, I can't see what part they play in the system and this might be what's stumping your players.

Hi!
  For instance, you can make a talent that replaces luck for a specific situation, use it to negate penalties for certain skills or use it to create a special Technique like Martial Arts.
  Also, there is a whole chapter on how they work with descriptions and examples. But I am pretty sure they haven;t read them...

So the Talents can have plenty of mechanical effects, just not the specific ones you mentioned? Cool.

Is the point of Talents to give each character some special ability or super power that is unique to them? In this case it may be that the combination of  having no limits on the colour side of things but plenty of rules about building the Talent might be a problem (especially when the players have not read the rules).

Probably the best answer is (as suggested above) to provide some examples that people can just pick up and use if they want or make sure players read through the system properly.