bf2 primary heightmap must be 1025x1025 16bit raw.
Terragen sometimes gives export errors, export as .r16 in world machine rename to .raw open in photoshop and look if the dimensions are right and not 1024x1024. 16bit-IBMPC-no or 1 header dont remember.
Compare the heightmap size, a 1024 size level should have exactly 2053kb large primary heightmap in windows explorer. Go to explorer menu -> show details.