Salem

i have the ground flat but i keep getting the message you cant build that here same with tryin to set out house

You can't build some things on forest terrain. Try paving the flattened land.

Maybe a stupid suggestion, but have you checked that you have enough Black Bile? Placing construction signs drain various levels of BB, but I do not remember the message you get when you have insufficient Bile.

ya wont let me pave it either

ya black bile is full .. really sucks i have 551 m2 that i cant build almost anyting on.. how does one get ahold of the dev's?..

Its not a dev problem. I can assure placing buildings works just as intended.

Are you on a Clay pit? (looks just like flattened dirt, but when you dig you get clay)
Are you in a forest? (need to pave the ground before you can build)
Is the land flat? (needs to be leveled before buildings can be placed)

I'm guessing your problem is the first one, since you want to build a kiln to make clay.

i didnt realize there are clay pits from what i gather you dig up dirt and use it in a clay tub. And i have not seen anything about not being able to build on certain land types anywhere

I have spent alot of time gettin the area ready just to not be able to use it let alone the time it has takin to get silver together for the expansion. Deffinatly a game breaker here.

Some people have to learn the hard way...

So, which problem do you think it was ?

Pave the ground. Get stones and pave it.
Adventure -> Pave

have you tried paving it?

What kind of tiles are you digging at (forest, grassland, etc.)?
Did you flatten the land yourself?
Did you use Ender's ctrl+L tool?
Is the area completely flat with ctrl+L?
Do you get clumps of clay into your inventory when digging in the flat area?