rear window defroster tabs

Hi Everybody, I have 94 GMC Jimmy. The rear window defroster tabs have ripped off the glass. I tried to solder the tabs back on, but my iron doesn't seem to be melting it at all. Any suggestions? Do I need to get an iron with a higher wattage or is the solder on the glass a special type? Thanks for any help.

i believe u need a special adhesivefor the defroster lines.

Update: I managed to get a stronger soldering iron and melt the solder so I could solder the tabs in place. That works much better than any adhesive. Everything is working fine now.