Have you ever had a problem with your health insurance?

Question

Any issues along the lines of you kept paying them, and then when you needed coverage, it was denied?

Answer 1

Yes

Answer 2

Often times claims deny because either a referral or prior-authorization wasn't in place at the time the services were rendered (if your plan is HMO), or the claim may have been coded incorrectly by the doctor (ex. a diagnosis for prostate cancer, but the patient is female). It happens all the time.
Have you called to find out why it denied?
Generally, as long as the care is medically necessary (and why else would you go to the doctor?) it is covered.

Oh, and if it was a referral issue, you can call the doctor and request that they backdate it, then call the insurance co. and ask that they reprocess the claim.

Good luck :)