Ack! Why I can't I build immortals?!?

I've applied 1.21f...and the following has happened:

I built a colony on some iron, but then the Zulu built a city, eliminating my colony. So I attacked the city and destroyed, then I built a new colony...
and I can't build immortals any more, despite the fact that Iron is online.

This has not happened to me before, and I'm wondering if the new patch had anything to do with it.

Here's the save, can somebody let me know if they're seeing the same thing?

EDIT: I wanted to make this a little clearer. I was able to build a couple immortals after I built the first colony, and they are still in the game. I just can't build any more.

Weird.. The iron doesn't show up on the city screen for me also. It only shows up after I build a city on a hill next to the iron.

You are pretty lucky though... I fortified the immortal unit near the Zulus and got a Great leader, Darius. Here's the save at 1050 BC:

http://www.civfanatics.net/uploads/Xerxes_of_the_Persians,_1050_BC.zip

I checked the Trade Advisor screen (in the original game), and Iron isn't showing up there either. Is there anyway to tell if this is patch related?

By the way, in the previous turn, the elite immortal was down to 1 red block, and still beat a healthy veteran Impi

Another thing you can do to make the iron show up (w/o building a city on the hill) is by trading Alphabet for The Wheel with the Zulus. There is a horse in your territory.

I restarted from a couple turns earlier, but again, building the colony resulted in no iron.

When I got The Wheel from the Zulus, it did appear (and I got it via Peace Treaty, instead of trade )

Too wacky

I have a possible reason(s) for you here...
I too have had this problem...

Check your trades with other civ's, perhaps you have traded your resource (iron) after first building the colony, made a trade agreement to sell your extra iron, then lost your extra iron, hence removing YOUR supply of it?

I almost blew a major war when this happened....

Rebuild the roads to your iron supplies. This fixed it for me when I lost my oil.

It seems Civ displays the improvements incorrectly, so if the display is buggy and shows an improvement that`s not there....

try the road rebuild thing, it often helps. Razing cities (even unintentionally when size 1) often gives Civ trouble since it will show RAIL even if neither of the two civs involved can build them!