[Hall of Famer]

Well this is NewComer center, it is for newbies to make a thread to introduce themselves and to socialize with other users. You should post it in a different subforum called 'Questions & Support', for general questions like this one. I will move your thread there this time, but in future its necessary that you keep what I said above in mind.

For your question, $mysidia->own is not a valid property name, it will have a null value. Calling method changecash() on a null value will give you an error message. You should change it to $mysidia->user, and the error will go away.