ExcelBanter - Help, i can't figure out 2 "And" operators!

i got code from http://www.mvps.org/dmcritchie/excel/delempty.htm to
be able to delete a row based on the same specific value in another
col.

i "attempted" to modify the code to work for my purpose but i've only
been working w/ VBA for a few months so i'm clueless as to what to do
exactly.

the original code is this:

Sub Delete_rows_based_on_ColA_ColB()
Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual
Dim cell As Range, rng As Range, i As Long
Set rng = Columns("A").SpecialCells(xlConstants, xlTextValues)
For i = rng.Count To 1 Step -1
If LCase(rng(i).Value) = "standard" _
And LCase(rng(i).Offset(0, 1).Value) = "card" _
Then rng(i).EntireRow.Delete
Next i
Application.Calculation = xlCalculationAutomatic
Application.ScreenUpdating = True
End Sub

and mine is this:

Sub DelRowOn_ColsBCF()
Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual
Dim cell As Range, rng As Range, i As Long
Set rng = Columns("B").SpecialCells(xlConstants, xlTextValues)
For i = rng.Count To 1 Step -1
If LCase(rng(i).Value) = "Customer Relations" _
And LCase(rng(i).Offset(0, 1).Value) = "[NULL]" _
And LCase(rng(i).Offset(0, 3).Value) = "[NULL]" _
Then rng(i).EntireRow.Delete
Next i
Application.Calculation = xlCalculationAutomatic
Application.ScreenUpdating = True
End Sub

what i'm attempting to do is to delete rows in which colB = "Customer
Relations", colC = "[NULL]" and colF = "[NULL]"

i'd appreciate any help,

- adam -