The problem maybe if the FPE file of that entity has the immobile=1 statement in it. Open the file change that to 0.
Save the file. Delete the .dbo file that goes with it.
Open the editor and reset the object. Then set immobile=1, and explodable=yes, and it should work for you now.
Slight bug when reading the FPE files with this statement and using explode with them.
Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz, 2400 Mhz, 4 Core(s), 4 Logical Processor(s), 8gb RAM, Nvidia gtx660, Windows 7 Pro 64bit, Screen resolution 1680 x 1050.