I created a pattern which is simply circles that repeat over and over again. I create a rectangle with the rectangle tool and include the pattern.
By going to Edit -> Modify colors -> redefine the colors of the illustration I can modify the color of my circles.
But I would like to create a color gradient from left to right.
So I tried Edit -> Modify Colors -> Horizontal Gradient but it shows me this message: You must select at least three paths to use this filter.
Do you have a solution to correct this error message or another solution to achieve this gradient?
I am using Illustrator CC 2017.
I thank you in advance .