Obect Required error when variable already set earlier in sub?

Hey folks! I have what I hope is an easy question to answer.

So I have code where I'm setting the following variables:

Set x = Workbooks.Open("S:\" & su & pe & "\" & ft1 & "\WPS.xlsm")
Set y = Workbooks.Open("S:\" & su & pe & "\" & pe & "\MasterWPS.xlsm")
Set z = x.Sheets(mo)
Set w1 = z.Range("A3:H12")
Set w2 = z.Range("A19:H28")
Set w3 = z.Range("A35:H44")
Set w4 = z.Range("A51:H60")
Set w5 = z.Range("A67:H76")

For the first few lines, whenever I call on w1.Copy, it works great.

However, if I have code later in the sub that looks like this:

Set x2 = Workbooks.Open("S:\" & su & pe & "\" & ft2 & "\WPS.xlsm")
Set y = Workbooks.Open("S:\" & su & pe & "\" & pe & "\MasterWPS.xlsm")
Set z = x2.Sheets(mo)

I get an Object Required error in the debugger. Do I have to set w1-w5 every time even though the range never changes? I'm thinking it has something to do with the fact that I'm re-setting z to refer to a new worksheet, but I figured since I'm re-setting z I wouldn't need to reset the w's as well since those just call on the most recent z variable.

But I'm also learning VBA as I go, so I know I'm using flawed logic here (if for no other reason than it isn't working :P). Is anyone able to let me know where I'm going wrong here, whether it be syntax or thinking?

Thanks!