Pulmonary / PFT's

Recently I have been noticing alot of denials from Medicare for spirometry CPT® 94010. We are billing our office visits with them and adding the -25 modifier to the office visits, also we are using payable dx codes. Not sure what could be going on?? I am new to this company as the previous biller retired and have no one to help me... any feedback would be appreciated.
2nd question.. Medicare is also denying CPT® 94640 when we bill our PFT's. We bill 82803, 36600, 94060, 94640, 94726, 94729, & j7620 (sometimes) Are we missing a -59 modifier on any of those codes. I have looked through the coding book and 94640 isnt bundled with any codes...

Thanks so much :)