Can't figure out why i'm Getting a 424 error when i use an IF/Then in Excel VBA

Part of a larger code, but I'm trying to fill out the blank spaces in a column that I can then delete later.

But if the column doesn't have blank spaces I need it to stop and move onto the next step instead.

I did this by having the code check column A, if Column A is blank than that means there are no blank cells in the column i'm checking.

However, whenever I ask this to do an If/Then statement to check if a particular nearby cell is blank it gives me a 424 error.

No idea what's causing this.

Range("D1").Select
Selection.End(xlDown).Select
ActiveCell.Offset(1, 0).Range("A1").Select

If ActiveCell.Offset(0, -3) Is Blank Then
GoTo Continue1
Else
End If

ActiveCell.FormulaR1C1 = "DELETEGREENELEPHANTS"
ActiveCell.Offset(1, 0).Range("A1").Select
ActiveCell.Offset(0, -3).Range("A1").Select
Selection.End(xlDown).Select
ActiveCell.Offset(0, 3).Range("A1").Select
Range(Selection, Selection.End(xlUp)).Select
Selection.FillDown

Continue1: