After the first start of PhotoLine you have to wait a few seconds because your PhotoLine isn’t registered yet. Therefore you should enter your serial number first.
The easiest way to do this is to press the button "Register..." in the splash screen. Alternatively you can wait, until the splash screen removes. After that select ?/Register... (on Windows) or PhotoLine/Register... (on Mac OS). Now the following dialog appears:
In this dialog you can enter the two serial numbers you find on the back of your CD cover. A more detailed description you can find in chapter 7.10.3 "Register".