I'm trying to build an XML for a soap request. cannot assign variable

Ok, after setting default it worked. Don’t now why that happens. But I got crasy while trying to set this value to that variable and I can reproduce that every time.
Btw. A very experienced employee recommended that I use multiple-assign when initializing multiple variables. This would be faster than individual assigns.
But you are right, if not needed they should not be used.
Kind regards