使用VBA打开Excel工作簿时，如何使打开的工作簿成为活动窗口?

I'm using a an xlsm file form that calls up a second form to ask the user to select which workbook to open. The VBA code will then open that workfile. However, I'm finding that in Office 2016, the file opens behind the original xlsm file. That is, it will not become the active window. I can use Alt+Tab to go to the open file, but the file will not interact with my keystrokes or mouse clicks until I Alt+Tab to activate the originating xlsm file. Then when I reactive the VBA-opened file, I can interact with it. That is, the file that VBA opened will not become active until I touch base back with the workfile that has the VBA code. I've tried a series of activeworkbooks, application.activewindow commands to activate the opened workbook to no avail. I'm using a an xlsm file form that calls up a s