Excel VBA won't save: creating 8-digit alphanumeric "filename" - excel

Question

I am new to VBA. I am using a "shell" macro to run another macro on a series of files. It won't save. I am going to include my code here and also a series of photos because the photos were the only way to show the result of hovering over the values in the code.
So, the error message is generating something I don't understand. But it is clear that the links in the code link to what the results should be, so I'm confused.
This is the code:
Sub SHELLforMacros()
Dim wbMatrix As Workbook
Dim strFileName As String
Dim strFileName As String
Dim newFileName As String
Dim strPath As String
Dim strExt As String
Dim objWorkbook As Workbook
Dim ws As Worksheet
Dim Sheetname As Worksheet
Set Sheetname = Worksheets(1)
Dim Worksheet As Worksheet
Dim rng As Range
Set rng = Range("A2")
strPath = "C:\Users\myname\Desktop\All_mricgcm3_files\45\Fall45\test\"
strExt = "csv"
strFileName = Dir(strPath & "*." & strExt)
While strFileName <> ""
Set wbMatrix = Workbooks.Open(strPath & strFileName)
Application.Run "'C:\Users\myname\AppData\Roaming\Microsoft\Excel\XLSTART\PERSONAL.XLSB'!Graph_NEW"
strPath = "C:\Users\myname\All_mricgcm3_files\45\Fall45\test\"
newFileName = Sheetname.Range("A2").Value
ActiveWorkbook.SaveAs fileName:=strPath & newFileName, FileFormat:=51
ActiveWorkbook.Close SaveChanges:=True
Wend
End Sub
What this macro is supposed to do is open a file, run another macro on the file (creating a graph), and then save the file with the same name but as an .xlsx file. Then open the next file in the folder and do the same, until it runs out of files. I realize the code may not be the most current. It is cobbled together from things I've found online. Thanks for any help.
Edit: UPDATE - I removed all the section on saving and closing the file from the "shell" macro and put it into the "Graph_NEW" macro. Now the "shell" macro is running fine. But I am running into the same issue with the "Graph_NEW" macro now. It is exactly the same error message as highlighted in the first image, only each time there is a new 8-digit alphanumeric "filename" that it is looking for. This seems like a very specific thing.
I changed the section in the following ways, successively, in an attempt to debug. I added With and End With around the section:
With WB
ActiveWorkbook.Save
newFileName = Sheetname.Range("A2").Value
strPath = "C:\Users\qmontana\All_mricgcm3_files\mric45\Fall45\test\"
ActiveWorkbook.SaveAs fileName:=strPath & newFileName & ".xlsx", FileFormat:=51
ActiveWorkbook.Close SaveChanges:=True
End With
I changed the name of the folder from "45" to "mric45" thinking that maybe it didn't like a number as a folder name.
I removed the "backslash" at the end of the strPath--and then the 8-digit alphanumeric string showed up as an error after the Fall45 folder, like this "C:\Users\myname\Desktop\All_mricgcm3_files\45\Fall45\777GTY78". Yet, as I've shown in the images, all indications are that it knows what file it is working with. There are no "blank spaces" in the pathname.
I tried taking the underscores out of the folder "All_mricgcm3_files".
I moved the line newFileName = Sheetname.Range("A2").Value to come before the strPath line.
Where is this 8-digit alphanumeric "filename" coming from?? (See error code, first image.)

Answer 1

Ok, it was a very simple thing, in case anyone else runs into this problem.
Took me two days to find out though --> I had somehow dropped a folder layer in the path name. The catch? The alphanumeric string was showing up at the end of the path name, not where the folder layer was missing. That's why I was thrown off because my focus was on the ending.
When I added that folder\ back in, I had no more problem with saving and the macro ran fine.