1. Spaces or unacceptable characters in the file name.

2. Using negative or non integer frame ranges (for example launching a job for frames -256 to 87 with a "by" value of .5).  An acceptable range would be 0 to 87 with a "by" value of 1.

3. Missing Textures (common problem in Maxwell Render).

4. Incorrect Render Engine selection such as choosing the Mental Ray for Maya Render Engine when the project is a Mental Ray for 3ds Max project.

5. Rendering 64bit projects in 32bit software.  Make sure to check that you have the proper bit selection under the settings tab on the "manage projects" page.  Please contact support@renderRocket.com to change this setting for jobs that have already been launched.