Can't build bridge in front of boardwalk

[kadoka66]

Why can't I build a bridge in front of the boardwalk?

I have seen other cities that have managed it, but whenever I try it gives me the error: building outside zone or something like that.

I have tried everything.

I put two lakes down that are connected to a road and then try and put the bridge down but to no avail.

None of the bridges work.