This happens when no bitmap file is selected for the command card in the game interface.
Either you have changed the bitmap by mistake or it got corrupted somehow.
Try to restore the user interface to the standard and test again, if this error still occurs your map file might be damaged.
Ye, thats it, u can go to Game Interface it also happened to me and i found it out myself, u must have opened a map and copyed something in this new and it has changed the interfaces of the new map or something like this... just put all to default in Gameplay Interface
I'm on a page about incorrect corrections, and spent the better part of like two hours trying to get someone to understand that -5^2 = -25, not 25, and then that post had comments get reposted because that group is self sustaining, and that person was in turn trying to explain what I just explained to them. And I'm taking that as a victory
I will be AFK for a couple of days you guys hold down the fort while I am gone. I will be checking in on my phone but that will severly limit me. Be back saturday!