Error Message:Select Method of Range class Failed

Dear all
I run a large code and a section of the code appears to fail

What is bizare is that I use exactly the same code before and it does not fail
(Both of the worksheets have been cleared from any previous data)

A message Select Method of Range class Failed appears

'Transfer Data
Set Rng1 = EMN.Range("C3").Resize(Numperiods, 1)
Rng1 = WorksheetFunction.Transpose(AnnualExternalMaintenanceCost)
Rng1.Select
Selection.NumberFormat = "$#,##0"
Set Rng2 = EMN.Range("D3").Resize(Numperiods, 1)
Rng2 = WorksheetFunction.Transpose(AnnualExternalMaintenanceCharge)
Rng2.Select
Selection.NumberFormat = "$#,##0"

Set Rng1 = IMN.Range("C3").Resize(Numperiods, 1)
Rng1 = WorksheetFunction.Transpose(AnnualInternalMaintenanceCost)
Rng1.Select 'Select Method of Range class Failed
Selection.NumberFormat = "$#,##0"

Any ideas why?

Many Thanks
Dora