question

I am using sql server data tools for visual studion 2012 for SSIS package development. Visual studio 2012 is also installed on my system. Facing issues with package configuration. I am following below steps. 1.Go to package cofiguration. 2.Expand any connection or variable to add value to config file. 3.Expand next connection or variable. And click on properties, previously selected connection values are disappearing. But its working fine when we expand all connections, variables and then select values. All the selected values should not disappear. it seems to be a defect. any help would be appreciated.