1) make sure you using latest release. It should be even better to try 3.2.2 RC4 (final RC before GA)
2) please show the code and share screenshot somewhere if 1) not helps..
I can't use the latest version since I am using Richfaces in my kinda old project we're using JSF 1.1. So I am forced to use 3.1.x (3.1.2 to be exact). Also another problem, the RichFaces skin is not applied to my page. It has transparent skin. How will I apply it? Isn't it out of the box. I specified skin in web.xml blueSky but it seems it doesn't work. I suspect that The skin is the problem.
I can't upload the image due to limited network in my office.
I could advice you to update to 3.1.6 which is the last versions with JSF 1.1 envirinment support. It contains many fixes also. And unfortunatelly we could not tell you if the next 3.1.7 will be done and when this happens.
I have already upgraded to 3.1.6. Unfortunately the problem is still the same. But when I run the LiveDemo of the version 3.1.6, ScrollableDataTable works fine. I mean the column header works properly. As per the installation of RichFaces I am not successful in running it with the applied skin. So I am suspecting the skin is the problem. I have already tried customizing the skin I've found in the following URL:
It actually works but again the problem is the column's header.
so seems you should use fireBug in order to find the style that brokes the markup. If you will not able to do this - you could add this issue to our jira.