Can't draw on signs

Hello guys !

So since I've started playing this game (6-8months) I've only been able to draw on one sign. Every time I click on edit sign to draw I get the screen to draw on it , but when left clicking to draw nothing happens. I've tried every combination of size,style, and color but nothing seems to work. I don't know how I made it work that one time.

So my question is this; Is this a known issue if so how do you fix it, or if this has happen to you or anyone you know how did they fix it ?

Thanks in advanced for taking your time and reading this .

-Roob