Market-Garden Pontoon Bridges

[Aetius]

While I was playing the Allies in a Market Garden campaign game, I had both bridges over the Waal at Nijmegen blown up (taking a considerable number of troops down, unlucky me).

Anyway, after I managed to get an engineer into a suitable position to begin a bridge over the Waal, I always had an error message.
Looking to the PDT value, Allied pontoon value was zero, and Axis 15. I managed to build a bridge playing the Axis in a test game, but I would expect it were the allies who had the resources to build such a thing.
Is this intended?

Rui