I'm able to replace the panel image with one of my own in Script04 of the lite-c tutorials and run the script successfully. When I start a new script file in a different folder using the exact same code, I get error messages. In both instances, I made sure that my image was in the same folder as the script.

can i see that code?

1) Make sure "use current file for test run" is checked in preferences > environment.
2) Make sure the script is saved as .c and not .wdl. When saving files you will have to manually type the extension.

It appears you were right. My problem was that I didn't save the script as a .c extention. Thank you.