Help needed, How Else Do I Signal To Her That I'm In The Mood?

Dear 9jababy Readers, 

 My wife and I have been together for almost 4 years now and in the beginning of our relationship we were having sex very very very often. But now I have to see a blue moon before getting some. Let's get this straight, 1. I'm not a dog
2. I'm not a pig 

I can throw any line at her and she still wont understand what I'm trying to hint at. 
I can be very blunt "babe, lets have sex!" and for some reason she must think I am messing around!  how do I get her to understand?!?! 

She is kind of a softy. If I even give off a vibe that I am going to confront her she puts up a guard because she thinks she is going to be yelled at.. (I'm not sure why she does this..)  I have sat down with her before to discuss that we need to be more sexually active..she agrees but then nothing changes!  AHhhh please help!