Can't Build over 18 blocks high

I'm talking about the PC edition.
When I said "xbox edition" I was talking about the border.

Please force a crash by pressing F3 + C for 10 seconds while in-game and attach the crash report ([minecraft|http://hopper.minecraft.net/help/finding-minecraft-data-folder]/crash-reports/crash-<DATE>-client.txt) here.

sorry, I have a mac so F3+c doesnt work because it just does this:
(see picture)

Try FN+F3+C.

What key does FN stand for?
o wait nevermind

---- Minecraft Crash Report ----
// Who set us up the TNT?

Time: 4/23/14 5:34 PM
Description: Manually triggered debug crash

java.lang.Throwable
	at ban.p(SourceFile:1405)
	at ban.ak(SourceFile:774)
	at ban.f(SourceFile:728)
	at net.minecraft.client.main.Main.main(SourceFile:148)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
	at blr.a(SourceFile:289)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [blw['FlufferKittens'/12, l='MpServer', x=89.59, y=257.32, z=7.10]]
	Chunk stats: MultiplayerChunkCache: 728, 728
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (0,4,0), Chunk: (at 0,0,0 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 91096 game time, 7690 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
	Forced entities: 8 total; [wo['Sheep'/1, l='MpServer', x=26.03, y=237.00, z=-31.09], wo['Sheep'/2, l='MpServer', x=21.84, y=237.00, z=-32.19], wo['Sheep'/3, l='MpServer', x=17.78, y=237.00, z=-33.13], wg['Cow'/4, l='MpServer', x=37.50, y=237.00, z=41.28], wg['Cow'/5, l='MpServer', x=63.97, y=237.00, z=-35.88], wg['Cow'/6, l='MpServer', x=87.91, y=237.00, z=50.13], wg['Cow'/11, l='MpServer', x=129.81, y=237.00, z=7.06], blw['FlufferKittens'/12, l='MpServer', x=89.59, y=257.32, z=7.10]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at blr.a(SourceFile:289)
	at ban.b(SourceFile:1972)
	at ban.f(SourceFile:737)
	at net.minecraft.client.main.Main.main(SourceFile:148)

-- System Details --
Details:
	Minecraft Version: 1.7.9
	Operating System: Mac OS X (x86_64) version 10.6.8
	Java Version: 1.6.0_65, Apple Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
	Memory: 56139936 bytes (53 MB) / 434937856 bytes (414 MB) up to 1069416448 bytes (1019 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 1.7.9
	LWJGL: 2.9.1
	OpenGL: NVIDIA GeForce 9400M OpenGL Engine GL version 2.1 NVIDIA-1.6.36, NVIDIA Corporation
	GL Caps: Using GL 1.3 multitexturing.
Using framebuffer objects because ARB_framebuffer_object is supported and separate blending is supported.
Anisotropic filtering is supported and maximum anisotropy is 16.
Shaders are available because OpenGL 2.1 is supported.

	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Anisotropic Filtering: Off (1)

That's because you're already at the top of the world. Try digging down first.

oh really? hmm. weird. I was building on the ground.

You mean I should dig down first and then continue building?

You used the "Tunneler's Dream" preset, that's for mining or underground building. There's not much space above it, you can, however, dig down. If you're planning on building above ground, use a different preset for your next world.

Okay thanks :'3