I just started a campaign as the Union. I have played through each scenario without any problems up until Malvern Hill, but now I can't start the battle. I can choose the division I want, but the start button will not highlight and I can't click on it. Please advise.

You have to stand a line directly in front of Union out of range, on the left send 2 regiments through forest to block the stream path and draw men off Union line. Place all cannons on the left of the main line and on the hill overlooking Malvern Hill on the other side of the river. Send another Corps south to the bridge and wait a whil for your cannon to back off Infantry and Artillery. Start the attacks from the south on the right with the other Corps after you cross the bridge. Split the Corps in the south sending 3 regiments to take one of the hills and the rest north. Force them to leave the line on the Northside of hill when then happen attack on the right, force them to steam and down the hill on the left into your 2 regiments blocking steam. Advance Advance everyone!!