Photon shielding problem

Dear fluka experts,

      I want to calculate the shielding properties of the materials for
383keV energy photon in vaccum. The thickness of the shielding
material is 5cm. I used the usrbdx card to calculate the one way
current of the incident photons and the one way current of the
emergent photons.
     Now i have a question:
     Why the current of the incident photons was zero (region from void to
target in usrbdx card) when the photon energy was 383keV. I used
"new-defaults" to calculate the problem. Where am i wrong?
     I have attatched the input file and any help will be appreciate!
    Thanks in advance!
    Regards,
    Z.F. Lee