Rearview mirror keeps falling off

I got an old pickup to do pickup things. It didn't have a rearview mirror or button when I got it.

No problem, I got a rearview mirror and button and an adhesive kit. 

I cleaned the inside of the windshield really well with a razor blade, then glass cleaner, then followed with rubbing alcohol, and followed the instructions on the Loctite brand kit. Stuck the button on, waited for the recommended cure time to pass. I put the mirror on, when to adjust it, it instantly popped off.

Tried again with a Permatex adhesive kit doing all the same cleaning as before except this time used Sprayway glass cleaner with the razor as step one. This time, I waited a full week for the button to cure before installing the mirror. Yay! Only, it fell off at some point in the night. 

Both times I dragged my finger across the glass outside of where I was gluing to feel for any residue. My finger skipped along making me believe the glass was clean/dry.

What gives? 

Any suggestions would be appreciated! 

Silicone residue for some reason? IIRC about the only thing that gets that off is denatured alcohol? I may have that wrong... But that's what I recall using before my best results recaulking where silicone had been.

See whether Permatex has a tech support contact?

I had this happen to me. FWIW the auto parts store said sometimes the glue is old or a bad batch.  I used the same brand and it has been fine.  I thought the store was giving me a line, but so far it’s stuck 

I tried two different NAPA glue kits on my C1500, finally bit the bullet and went to a glass shop.  He hit the windshield with acetone, then a dab of Lok-Tite, unfortunately he held the tube in such a way that I couldn't make out the label.  Less than a week later it popped off again.    Went back, talked to the nice girl behind the counter, the grumpy glass guy came out and did it again.  When he tried to charge me another $10 she punches him in the arm and cranks at him.   It was free.

Go to  a glass installer.

Yep, local glass shop can hook it up in no time. My local shop did mine for free.

Last time I did one I used a adhesive kit that had two parts.  Mixed them together like epoxy and stuck the puck/button/ mount on the glass and as far as I know it is still on there.  The mirror kit with the single glue did not work for me either.

I buy the kit that has a cleaner and little primer pad along with the tiny tube of glue.  I generally can't even glue my fingers together, and these kits work.  

Loctite, maybe?  Permatex, could be.  Same company now anyway.

I did the mirror on my new to me pick up cleaning with a razor blade and carb cleaner. Cleaned and scraped 2 times and then once more with carb cleaner. I used crazy glue and it is holding fine.

Mine fell off after the glass shop replaced truck's windshield.  Fell off in about a week.  Went back and the owner said that the buttons are sometimes not flat.  Took a new button, sanded it with what looked like about 320 grit on a piece of plate glass and then wiped it with acetone.   Went out and scraped the windshield, cleaned it with acetone, coated the glass where the button was located with an activator, and then applied the button with a drop of glue.  Held it on the glass for a minute or so, then put a piece of blue tape over it.  Told me to wait to install the mirror until the next day.

Been on there for two years now.

Thanks for the suggestions. 
 

The two products I've tried were glue plus activator. The Loctite uses a glass tube in a plastic tube with a felt applicator for the activator and the Permatex uses a wet nap style activator. Both also had a tiny glue tube. 
 

I have a 2-part epoxy that has rear view mirrors as a suggested use so I'll give that a shot since I have it. Next, I'll run by the glass shop. 
 

What a beaut otherwise 

I've done a bunch over the years (I'm old & drive junk) Can't recall ever having an issue. Don't know, it's not like I have never effed things up.

I usually use a good brand of cyanoacrylate adhesive and clean the windshield with brake cleaner. 

Step right this way...