In many countries, saying no is not very appropriate. I once observed a conversation between a shop attendant and a customer, here in Amsterdam, that illustrates this.
A lady stood at the counter of an optician, and asked the girl behind the counter whether they had one-day-use contact lenses. The girl (I guessed she was of Iranian descent, or something similar) made an apologizing and troubled facial expression, but didn't say a word. The lady looked confused and said: "Excuse me, did you say no?" She forced the 'poor' girl to actually say the word 'no'.
In the Dutch culture, people want you to say what you mean. No means no, and 'no' is not a bad thing. I heard that Americans also have a difficulty with saying no. They'd rather say something like: 'I'll see what I can do'. How is that in your culture?