The PHOTFLAM header keyword is incorrectly populated in output images created by Multidrizzle 3.3.6 (released in STSDAS 3.11), and versions that preceded it. This bug does not affect the output image data itself, just the value of its PHOTFLAM header keyword. This problem only affects WFPC2 output data, the output data from other instruments is fine. This bug will be fixed in an upcoming release of Multidrizzle version 3.3.7 (in STSDAS 3.12), due to be available in June, 2010.
For more information, please see The PHOTFLAM Advisory memo.