TileLab products are made by a company called "Custom Building Products". If there is no Customer Service 1-800 phone number on your jug of sealer, I would Google "Custom Building Products" to find their web site, then click on the "Contact Us" link and talk to someone there as to what may have gone wrong. It's very possible that you simply need to seal the grout multiple times to make it effective. I have no experience with that product, so I really don't know what may have prevented it from working.
If you want to try a new or different penetrating sealer, DuPont is producing a line of masonary and grout cleaners and sealers called "Stone Tech". I haven't used any of these products, but if they're being produced by DuPont, at least you can be sure that they should work as advertised because DuPont has a very impressive amount of technical expertise at it's disposal. If DuPont can't make a grout sealer that works, no one can.
DuPont? StoneTech® Professional
I would click on the Contact Us link on the above web site and talk to someone at DuPont about where to go from here. Tell them what you did, tell them what Custom Building Products said about why their sealer didn't work, and ask Dupont what the safest route forward is.
In the 21 bathrooms in my apartment block, I use a film forming grout sealer. You used a penetrating sealer which gets absorbed into the grout and dries there. It changes the surface of the grout to make it repel water so that water simply beads up and drips off the grout. A film forming sealer simply coats the grout with a clear impermeable film.
The grout sealer I use in all of my bathrooms is simply called "Grout Sealer" and is marketed by the Glaze 'N Seal company of California:
Glaze N' Seal
Theoretically, penetrating sealers should last longer on a shower wall or on a floor than film forming sealers, and that's because the erosion of the shower spray and wear and tear from foot traffic will gradually erode a film forming sealer. The penetrating sealer penetrates some distance into the porous grout, and is therefore protected from foot traffic or from the erosion of the shower spray, and therefore should last very much longer than if it were exposed to both.
PS: You don't need to know the rest
Somebody at 1-800 Customer Service might get on your nerves by asking you how you KNOW the grout is wet. If so, tell them it's because it's darker after having a shower than before. The reason why rocks and grout and your blue jeans are darker when they're wet is because water, being much denser than air, has a refractive index closer to that of solids than it does to that of gasses (like air). As a result, incident light hitting wet grout will bend less at each grout/water interface than it will at each grout/air interface. The result is that light travels in a straight-er line through wet grout than it does in dry grout. That, in turn, results in less light being reflected (and refracted) back out of the grout to your eye. Consequently, you see less reflected and refracted light when the grout is wet, and that is what makes the grout appear darker when it's wet.
So, if someone tells you the sealer is working, and the grout is dry, but only looks wet, then any change in colour of the grout as a result of water coming into contact with it (or difference in colour between grout that got wet and grout that didn't) is proof that's BS.