Problem to select the attribute in aggregate list in microflow

Hey I am using mendix 9.0.3 version and was doing the intermediate module from mendix academy  “create an app with advanced page building concepts”  In 4.5 Adding request (4.5.1 finishing up) of that module In microflow to calculate the total amount of wizrard 3 page  I am not getting the option to select the attribute to sum the price in that microflow I am attaching the snapshot can anyone help me out? 
1 answers

Does you entity have the needed attribute?

Is the type of the attribute decimal or integer (you can’t sum up a string)?


If answeres are yes, I would suggest to use a stable version of Mendix to do your training. 9.0.3 is a beta release and may contain bugs.