WHY SUCROSE DOES NOT FORM OSAZONE?

We know that sugars are of two types, reducing sugar and non reducing sugar. Those sugar molecules which have a free aldehydic and ketonic group and can reduce Tollen's and Fehling reagents are called reducing sugars. For example, glucose. 

Sucrose is a non reducing sugar as the OH groups at the both the anomeric carbon atoms are involved in a bond. 

Hence sucrose will not give Benedict's test, Fehling's test and tollen's test, which is given readily by most of the aldehydes and will form not osazone because of the absence of free aldehydic or ketonic group.