I can see that you are betting below 30 SEK, which is the minimum allowed amount to bet in Swedish kroner.
However, please keep in mind that in order to make a bet below the minimum, the program still places a larger bet, of exactly 30 SEK, first and then modifies it to a smaller amount -- there is no other way to do it.
So make sure you have enough funds in your account to cover your intended bet + the initial 30 SEK bet. I think the error message could be caused by the lack of funds in your account.