How to suppress “SQL Server Login” window on Excel?

I am using Microsoft Task Scheduler to run Excel models everyday. The models retrieve data from the database and do stuff. The connection strings contain all information(username, password etc.) needed to connect to the database. However, I get this prompt sometimes:

SQL Login Prompt

When I click “OK”, everything goes fine, so I need the Excel to just click OK because the username and password are already there. I want to suppress this window by clicking OK. Otherwise the models stop running and wait for me to click OK manually.

I checked for the solutions on the web but did not encounter a working one. I tried to change the connection string in various ways but it did not work.

Does anyone have any idea on how to solve this issue?

Thanks

Edit: Here is the code I am running on VBScript for Task Scheduler.

'Input Excel File's Full Path
  ExcelFilePath = "MyExcelFile"

'Input Module/Macro name within the Excel File
  MacroPath = "Macro1"

'Create an instance of Excel
  Set ExcelApp = CreateObject("Excel.Application")

'Do you want this Excel instance to be visible?
  ExcelApp.Visible = True  'or "False"

'Prevent any App Launch Alerts (ie Update External Links)
  ExcelApp.DisplayAlerts = False

'Open Excel File
  Set wb = ExcelApp.Workbooks.Open(ExcelFilePath)

'Execute Macro Code
  ExcelApp.Run MacroPath

WScript.Sleep 10000

'Input Module/Macro name within the Excel File
  MacroPath = "Macro2"

'Execute Macro Code
  ExcelApp.Run MacroPath

WScript.Sleep 10000

'Save Excel File (if applicable)
  wb.Save

'Reset Display Alerts Before Closing
  ExcelApp.DisplayAlerts = True

'Close Excel File
  wb.Close

'End instance of Excel
  ExcelApp.Quit

The excel VBA code for Macro1 is just

Sub UpdateModel()
ActiveWorkbook.RefreshAll
End Sub 

command for pivot tables which are getting data from the database.