Have you tried commenting AActor::TakeDamage and compiling? If it works the problem is there.
If not, the problem could be in the order of the .h files being included, try changing the order of DamageType.h.
Have you tried commenting AActor::TakeDamage and compiling? If it works the problem is there.
If not, the problem could be in the order of the .h files being included, try changing the order of DamageType.h.