For each portfolio, a certain amout of server space is available. If you have used up all this space, you may have included pictures that are too large.
Make sure to check that your .jpg file is not unnecessarily large, approx. 1 Mb per picture. You can open the file in Paint to check the size. Use ‘Resize’ to make the picture smaller and use ‘Save as…’ to save the file as .jpg. Beware not to overwrite the original file, since the quality of the resulting file will be degraded!