Photoshop 27.6-7 Brush tool stop allowing pixels to poplate on screen when "attempting to draw" via using the Tool

Default install when I first started using a file or created from scratch the Brush Tool would allow me to select it in the tool bar; however when using on an image of any kind it fails to output any pixels.  Suggestions?  Due know that the Seagate Portable Drive is for Scratch Disk tasks/use.