I have 2 keys that came with the car. Neither will unlock via keyless. I have tried the process 4-5 times to no avail. I also confirmed the LED in the end of the remote lights if you hold it down 2-3 secs. Anyone know what I could be doing wrong or could post the correct process?

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1996 E300D
1996 E320 Wagon 4MATIC
2003 Jetta TDI- GLS, 5-spd
1997 Passat TDI
2002 F350 Crew cab 4x4 Powerstroke
Jacobsen HR 15' cut ZTR w/ 80 HP Perkins diesel
Hustler 6' front deck with 28HP Kubota diesel