Verizon Fios 5.1 Sound

[mreilly611]

I have Verizon Fios and I watch some shows on CBS & NBC like David Letterman and Jay Leno plus The Late News. I have a Onkyo 875 receiver and when I hit display on receiver when shows are playing it says Dolby Digital 5.1 but I am not getting any sound from Center speaker the voice is coming from the front left and right. When I watch shows like CSI (CBS) and Chuck (NBC) I am getting 5.1 sound and center speaker is working. Does anyone else have same problem with no sound from center when show says 5.1. On my receiver I use Dolby D EX as my sound field.