One reason that listening hours per week per capita to Internet radio are increasing (according to both the annual Arbitron-Edison "Infinite Dial" study and easy math you can do with monthly Triton Digital press releases) and listening hours per week per capita to AM/FM radio seem to be declining (if you're an Arbitron subscriber, check Persons Using Radio (PUR)...
Ad insertion isn't easy
If you're a webcaster struggling with issues involving ad insertion, you can be comforted by the fact that at least you're not alone -- the multi-billion dollar corporation NBC (owned by the multi-multi-billion corporation Comcast) is having issues too.
Just as my grandmother had what she called "her shows" (e.g., the noontime soap opera "The Edge of Night"), I have my shows too. In my case, they're primarily the Thursday-night comedies on NBC (e.g., "30 Rock," "Parks and Recreation," and "The Office").
And because I'm trying to be cutting-edge, I'm trying to "cut the cord" in terms of paying for monthly cable TV service by trying to watch these shows on my iPad via NBC.com.
However, at least for me personally, NBC is doing a very poor job of ad sales and/or insertion. Basically, the only spots they're delivering to me are promos -- either for "The Voice," which is a show currently being ridiculed on "30 Rock" (so probably "30 Rock" fans are not ideal prospects for it) or "Chicago Fire," which they're currently telling me is "Debuting October 8th!" even though we're now into almost mid-November.
So, take comfort: You may not be doing it perfectly, but given your relative corporate resources, you're not doing THAT badly.