Error 16: Expression Too Complex - Nested Select Case - vba

Question

I am getting a "Run-Time Error 16: Expression Too Complex" for the sencond code block. I read online that the maximum allowed number of nested expressions is 8, but if nested statements are defined by every "Select Case," then I haven't yet hit that. Is it possible it's because the Cases are dependent upon a variable? The first code block shows the possible values of egapend, while the second shows the code that is returning the error. Thanks in advance for your help.
First:
Select Case ge1e2
Case Is <= 0
Select Case ge2e3
Case Is <= 0
egap18a = 0
egap18b = 0
Case Is > 0
egap18a = 0
egap18b = ge2e3
egapend = Sheet1.[z1IE]
End Select
Case Is > 0
Select Case ge2e3
Case Is <= 0
egap18a = ge1e2
egap18b = 0
egapend = Sheet1.[z1CZ]
Case Is > 0
Select Case ge1e2
Case Is >= 180
egap18a = ge1e2
egap18b = ge2e3
egapend = Sheet1.[z1CZ]
Case Is < 180
egap18a = ge1e2
egap18b = ge2e3
egapend = Sheet1.[z1IE]
End Select
End Select
End Select
Second:
Dim e1length As Long
Dim e2length As Long
Dim cp121 As Boolean
e1length = DateDiff("d", Sheet1.[z1CZ], Sheet1.[z1DA])
e2length = DateDiff("d", Sheet1.[z1IE], Sheet1.[z1IF])
Select Case extendedgap
Case True
Select Case egapend
Case Sheet1.[z1IE] 'end of egap is start of E2
Select Case e2length 'was borrower employed by E2 for more than 6 months?
Case Is >= 180
cp121 = True
Case Is < 180
Select Case ge1e2 'if not, was there a gap between E1 and E2
Case Is > 1
cp121 = False
Case Else
Select Case DateDiff("d", Sheet1.[z1IE], Sheet1.[z1DA]) 'If not, was employment between E1/E2 6 mos?
Case Is >= 180
cp121 = True
Case Is < 180
cp121 = False
End Select
End Select
End Select
Case Sheet1.[z1CZ] 'end of egap is start of E1
Select Case DateDiff("d", Sheet1.[z1CZ], Sheet1.[z1DA]) 'was borrower employed by E1 for at least 6 mos?
Case Is >= 180
cp121 = True
Case Is < 180
cp121 = False
End Select
End Select

Answer 1

It's really just a big nested conditional structure. Don't use Select...Case for that. Use it e.g. when you're looking at some enum value:
Select Case MsgBox("Yes, no, or cancel?", vbYesNoCancel)
Case vbYes
'stuff
Case vbNo
'stuff
Case vbCancel
'stuff
End Select
Refactoring step 1: Turn all these 2-branch Select...Case blocks into If...Else...End If blocks. That should already take care of the "expression too complex" compile error.
Refactoring step 2: Implement Boolean assignments as such:
For example in one place two places you have:
Select Case DateDiff("d", Sheet1.[z1IE], Sheet1.[z1DA]) 'If not, was employment between E1/E2 6 mos?
Case Is >= 180
cp121 = True
Case Is < 180
cp121 = False
End Select
Replace that with:
cp121 = (DateDiff("d", Sheet1.[z1IE], Sheet1.[z1DA]) >= 180)
Refactoring step 3: Extract functions and procedures out of the If and Else branches where applicable; eliminate the duplicated branches, Don't Repeat Yourself.
Once you have something that works, take it to Code Review for further refactoring and simplification ideas.