I'm not sure............they came off the same site and I put them in the same way. I'm computer illiterate though, so I'm sure it's something I did.
One difference between the two is the file name of the image. The first one the file name is "128745432033032292.jpg" the second is named "funny-pictures-cat-will-neuter-your-dog-if-he-steps-on-her.jpg" The reason you cannot see the second (presuming this is from work) may be that your company's "net nanny" is blocking the image due to the word "neuter" (or maybe even the words "funny-pictures") in the file name.