Band did not migrate on gel electrophoresis (SDS) - (Nov/17/2014 )

Please could someone explain why this band did not migrate on lane 2 and why the standard on the right is very light.

Tell us what you did - how the samples were prepared, what are they (purified protein, bacterial cell lysate, yeast cell lysate... etc)?, how they were run.

Troubleshooting is all about details.

How's the buffer chamber? Leaky? Or maybe you loaded the lane on top of an air bubble?

How did you handle the gel after running? Did you precipitate the proteins immediately or left the gel in water? Maybe the amount of liquid too low, and the gel has warped above surface in one side, causing uneven staining.

the sample which didn't run is probably aggregated and too large to enter the gel (yes, it can be even in the presence of sds).

the standard is light because less was loaded than you expected.

what is your visualization method?