I click on the signature button in the Preview.app toolbar:

![](https://i.stack.imgur.com/qytdd.png)

The following box pops up:

![](https://i.stack.imgur.com/WjvW8.png)

I click on the `Click Here To Begin` button. The box is now ready for input:

![](https://i.stack.imgur.com/U3k5G.jpg)

However, I cannot get any markings at all to show up as my signature. My box always looks like the above image.

I've tried doing the above in an image document and a PDF document. I've tried holding down the trackpad while writing and not holding the trackpad down while writing. I've tried using a mouse.

Is there a fix for this bug, so that I can use my Macbook trackpad to write my signature?

Note: the Camera-based signature method technically works on my machine. However, its rendition ability isn't great.

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OS X El Capitan, version 10.11.6. 

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