如何使用其定义的变量打开工作表

I am trying to open a worksheet that is a defined variable. I have a list of ID's and each of those ID's have their own worksheet where the name of the worksheet is the ID number. I am wanting to use the first ID value and assign it to a variable, then open the corresponding worksheet using that variable. Here is the current code I have. The error message is "Object Required".I am trying to open a worksheet that is a defin