The results of Photoshop scripts and actions are directly related to the brightness and contrast of the original image used. Below is a test image with a range of brightness and contrast values that your image may have. The effect of the Rough Pencil script below, shows the difference result that these values would yield.

If your result is too light, dark, flat or lacking in details, you could adjust the original's tonal values, with more or less brightness & contrast, to enhance the results.