OPEN STAAD Issue- Not getting Beam Width & Depth

I get stuck with the highlighted line and get  "Run Time error 438" when I run the following code.

Please help....

Sub beamppt()

Dim pdWidth As Double
Dim pdDepth As Double
Dim pdlength As Double
Dim SelBeamsNo As Long
Dim Beam As Long

Set objOpenSTAAD = GetObject(, "StaadPro.OpenSTAAD")
SelBeamsNo = Cells(4, 1)             (This cell has the total no of beams)

For i = 1 To SelBeamsNo
Beam = Cells(3 + i, 2)                      (This cell has the beam numbers)
objOpenSTAAD.GetMemberWidthAndDepth Beam, pdWidth, pdDepth
Cells(3 + i, 3) = pdWidth
Cells(3 + i, 4) = pdDepth
Next i

End Sub