Can't build bridge

[Phat_Cooch]

im new to the game so im probably missing something. Im playing on the river map and need to build a bridge to get to the iron deposit, it says it needs 45 planks, i have over 60 and it just wont let me place the bridge, is there a point in the game i need to reach before it allows me to place the bridge or is this a possible bug? i cant find anything about this anywhere online, pls help

[pckirk]

Distance span is longer then max size of bridge.

[Phat_Cooch]

i figured it out, i cant build a bridge on the bend of a river. bit silly