1999 Ram 1500 V8

My 1999 Ram was starting fine until I found a spare key and tried it. Started OK first time, now cranks but no ignition! I'm at a loss to see how this "kinda crusty" key would screw up the ignition. Everything on the truck works fine otherwise. Tried to trace power down the line, made it as far as the fuse box under the hood. Power to there and fuses seem ok. Notice that when key is turned to on/ignition, there is no power at coil connector (via test light). Anyone got any ideas as to how to "chase" this problem? Thanks

Debris in the ignition switch?

Was there any special security installed in your truck?

Thanks for the reply. I've been out of town for a week, so I couldn't respond right away.
I checked the ignition switch with a test light. All circuits (except starter) go hot when switched on. I've checked the fuses at left side of dash, all look ok. I've replaced the automatic shutdown relay left side of engine bay, still no power to coil. Cleaned up grounds on firewall (from computer and rear of engine), still no power to coil / no spark when turning over. I've got the wiring diagram, but I'm no expert on following the sequence. I guess I'm looking for a logical step by step power check sequence to trace the system from ignition switch to coil/plugs/injectors. Hopefully, someone can give me some hints on where to start. Thanks in advance