LinuxQuestions.org - tesseract stopped. error without explanation.

I like tesseract. I downloaded version 3.02, and started using it right away with excellent results. Then it stopped working, with the following error:
tesseract ltr-996h-p1.png ltr-996h-p1
Tesseract Open Source OCR Engine v3.02 with Leptonica
Cannot open input file: ltr-996h-p1.png

I was using the same programs to scan and prepare the png, or tif files (gimp and xsane). No description of what the error means. the help feature doesn't help, and man tesseract is no help either - maybe because I don't understand their termnology.

If you know where I should go from here, pleae help me out. Or maybe you now where there is some really thourough and understandable documentation on tesseract.

Thanks.