BC30420 'Sub Main' was not found error in a Windows Form app - vb.net

Question

I've created a Windows Form application. It is my understanding that you do not have to have a Sub Main() in a Windows Form app. However I'm getting this error when I build my project:
BC30420 'Sub Main' was not found in 'LoanCalculator.Module1'.
First of all I don't know why it's saying 'LoanCalculator.Module1'. Both my form and my class are named LoanCalculator.vb. When I started the project I started writing the code in the original module. Then I added a module, named it 'LoanCalculator' and moved what code I had written to that module and finished it there. I deleted the original module. Now it builds fine with the exception of this one error. Here's my code:
Imports System.Windows.Forms
Public Class LoanCalculator
Private Sub Calculate()
Dim str As String
Dim intLoanAmt As Integer
Dim intDown As Integer
Dim intFees As Integer
Dim intBalance As Integer
Dim dblIntsRate As Single
Dim intLoanTerm As Integer
Dim sngInterestPaid As Single
Dim intTermMonths As Integer
Dim dblMonthlyPmt As Integer
Dim intTotalPaid As Integer
Dim dblYon As Double
Dim dblXon As Double
Dim dblZon As Double
If Not CheckInput() Then
Return
End If
intLoanAmt = Convert.ToInt32(txtLoan.Text)
intFees = Convert.ToInt32(txtFees.Text)
intDown = Convert.ToInt32(txtDown.Text)
intBalance = Convert.ToInt32(intLoanAmt - intDown + intFees)
intLoanTerm = Convert.ToInt32(txtTerm.Text)
dblIntsRate = Convert.ToDouble(txtTerm.Text)
intTermMonths = intLoanTerm * 12
dblYon = dblIntsRate / 1200
dblXon = dblYon + 1
dblZon = Math.Pow(dblXon, intTermMonths) - 1
dblMonthlyPmt = (dblYon + (dblYon / dblZon)) * intBalance
intTotalPaid = dblMonthlyPmt * intTermMonths
sngInterestPaid = intTotalPaid - intBalance
str = "Loan balance =" & Space(11) & intBalance.ToString & vbCrLf
str = str & "Loan Term =" & Space(16) & intLoanTerm.ToString & " years" & vbCrLf
str = str & "Interest paid =" & Space(17) & intTotalPaid.ToString & vbCrLf
str = str & "Monthly payment =" & Space(5) & dblMonthlyPmt.ToString
lblResults.Text = str
End Sub
Private Function CheckInput() As Boolean
Dim strErr As String = ""
If txtLoan.Text.Length = 0 Then
strErr = "Enter loan amount" & vbCrLf
End If
If txtDown.Text.Length = 0 Then
strErr = strErr & "Enter down payment" & vbCrLf
End If
If txtInterest.Text.Length = 0 Then
strErr = strErr & "Enter interest rate" & vbCrLf
End If
If txtFees.Text.Length = 0 Then
strErr = strErr & "Enter fees" & vbCrLf
End If
If txtTerm.Text.Length = 0 Then
strErr = strErr & "Enter loan term" & vbCrLf
End If
If strErr.Length > 0 Then
MessageBox.Show(strErr)
Return False
Else
Return True
End If
End Function
End Class
How can I fix this?