Got my visit visa rejected

[whitegrim]

Hi,

I just got the refusal of my family visit visa and I was not hoping for that. The reason for refusal is that I have not shown my source of income. I am currently studying in Germany doing Masters and work on the internet. By working on internet I don't have any papers that suggest I am self employed. Moreover, I don't have any tax returns as well as it is still not a one year to submit my tax returns since I started working. So what should I do now? I am thinking of appealing and telling them that I work as a freelancer and cannot have tax returns because I am working like this for less than a year. What else could I write or add up with the appeal??? I would greatly appreciate any assistance.