Welcome to advertising on the internet. Unfortunately you are experiencing what every single other advertiser does, phony results. The Wall Street Journal reported some time ago that they did an investigation and found that 30% of all internet traffic is bogus. So what Google Analytics is not recording is that bogus traffic. What is bogus traffic? Computer bots in Russia and China (highest two offenders) roam the internet and click-click-click on ads or page refresh over and over in return for a kickback. Since ads are either paid by click or paid by impression, this generates $1000s in income for the website the bots crawl on. Effectively this is stealing from the one paying for the advertisement. However since many websites aren't managing their own ad space, but instead leasing it out (AKA Project Wonderful) they have no direct part in the theft. In our opinion, Google AdWords is one of the worst offenders on bogus traffic as we have paid as high as $5/per click through the bidding system and nothing came of it.
Having spent $10,000s on advertisements in the past, we would like to caution all creators to be very protective of their marketing dollars because its really easy to spend it and gain no results. Here are some basic facts. The click thru rate on the average internet ad is .1%. That is for every 1,000 impressions you will get 1 click. Most advertisers sell their space in terms of CPM which is cost for 1,000 impressions. A very common price is $10/CPM, or $10 for 1,000 impressions or $10 per click. The reason for the low click thru rate is people ignore ads. Plus 300 of those impressions are bogus.
If the CPM of an advertiser is $10, ask yourself, is one click worth $10? Unless you are selling a product that has a large profit margin, no. Even a CPM of $1 is too high for advertising Tapastic, because there is no way you will get $1 back in revenue.
Based off Kickstarter Tapastic results like 4-Panel Life, the average subscriber is worth approximately $.50/each in gross income on future print sales. Gross income, not net, because you have to pay to print the books and ship them (and shipping is the biggest expense of all). You also will make some money on views, about $1 per 3,500 raw Tapastic views (as many use adblock and mobile only users see no ads). Finally there may be some income from donated coins but that feature is still in the works so we can't give any numbers on that yet.
What we are trying to get at is that advertising your comic is not a great return on investment unless you are paying a very low rate. Currently we only are advertising at one place right now and that is at .$04/click, and even at that low rate, we are are losing money. However we have gained a number of subscriptions from it so it's useful in helping our comic grow. We also realize that early on, you will lose money growing your early base but will make it up later when the early base attracts a larger and larger base.
Think of advertising your comic as a snowball rolling downhill. It starts off really slow (very expensive) but as it gains momentum it gets going faster and faster until rolling freely on its own ("viral", free media mentions) and hopefully becoming an avalanche of success. One such example is GamerCat, which has added over 8,000 subs in the last few months.
So you are going to have to pay a lot up front to get the ball rolling for hit-and-miss results. It's your call on what that is worth to you. To us its $.04/click, or $.04/CPM, but to you it may be more.
Personally we looked over Project Wonderful, but decided against it as the CPM was too high.
Wishing you the best of luck.