Somehow I can´t buy/sell stocks the last two days. Every time I get the ´invalid price´ error no matter what.
In both ways (buy and sell) I enter the shares and price as followed:
Amount: 1000
Price: 100.00 (a dot and 2 numbers after the decimal)
The price is within 10% of the current price.
Is there something I´m missing?
Have you already buyed shares with this company? Maybe is a question of equity… Or, as I have experienced a question of decimals (dots instead of comma). But you have already said is a dot! 
To be more exact:
I got 3475 shares of Air Broad Cross [Meigs] which I would like to sell. I´ve been selling and buying some of his shares before, but somehow the AS doesn´t let me. As said, I´m using a dot instead of a comma in the price and no commas in the ammount (one thousand shares : 1000 not 1,000). The price is within 10%, but even then it tells me ´invalid price´. Would be nice to get a more detailed error feedback form the system …
The price must be within 10% of the stocks book value, not the current selling price. This might be tripping things up.
Well… You would expect to able to sell your shares for 490.00 AS$ when the current stock value is 492.51 AS$ 
I created a ticket, let the support team figure it out. Hopefully they can give me a sensible reason and/or tell me what I´ve missed.
I had the same issue several times when I tried to buy or sell shares. But I never bothered to raise a ticket. I am curious what the reply is though.
I don’t understand what you are saying. If you look at the stock data for a company, you see something like -
Current 199.97 AS$ Quote date 25.06. 00:0
So, if this is the current selling price and not the stocks book value, then what is the stocks book value, the book value in my portfolio?
I have some shares in this company like this -
Stock Share Book value per share Market value per share
1,609 0.30% 172,725 AS$ 107.35 AS$ 321,749 AS$ 199.97 AS$
However, the system lets me make a sell offer for 222 AS$ minimum price, which is more than 10% of 199.97, and certainly a lot more than the book value.
Book value of the stock (maybe not the correct technical term) is the value of the airline’s assets divided by number of shares. The price of the stock is reset to this daily (at midnight GMT maybe?). If someone sells stock stock for a different price than this the quoted price will reflect the most recent selling price.
For example-
stock in ABC airline is worth $100 (the company has $100,000,000 is assets and there are 1,000,000 shares outstanding).
DEF holding co sells 1,000 shares of ABC to HIJ holding for $110. This is legal because $110 is only a premium of 10%.
That same day HIJ tries to list ABC for $121. This seems reasonable since the price shows $110 (due to the sale from DEF to HIJ) and $121 would only be a 10% premium, however because the book value is still only $110 this can’t be done.
… At least thats how I understand it. I haven’t been very active in the stock market as of late.