It works fine here - given that a cell width of approximately 6 inches is pretty large?
Option Explicit
Sub Macro1()
Dim oPic As InlineShape
Dim plotLocation As String
Dim CellRange As Range
Dim FileName As String
plotLocation = "D:\My Documents\My Pictures"
FileName = "Filename.jpg"
Set CellRange = ActiveDocument.Tables(1).Cell(1, 1).Range
CellRange.End = CellRange.End - 1 'Remove the cell end character.
Set oPic = ActiveDocument.InlineShapes.AddPicture(plotLocation & "\" & FileName, False, True, CellRange)
With oPic
.LockAspectRatio = False
.Width = CentimetersToPoints(15.5)
.Height = CentimetersToPoints(10)
End With
End Sub
Bear in mind, if the aspect ratio of your picture is correct and the width of the picture is larger than the cell width. If you set the cell width to fixed, the image will shrink to the width of the cell and the height will maintain its aspect ratio.