I can't think of a way, I checked the problem and the WHERE statement has to be used for 80 and 90 id's

I have learned it

SOLVED. For anyone using this as an archive, in the program to pull the data, the loop must be at 1 not 0. and secondly, after you close the loop, you need a loop counter. looks like CharlieMay & Lar3y taught me some nice stuff!

The lines where I added the comment appears yellow when I click the Calc button. the "decLABOR_CHARGE" I newly declared at the top. It has a decimal value of 20. Replacing the dblPart line with your statement still gives out the same error when it comes time to calculate.

Both lines read the same error when they are tested.

" Conversion from string "" to type 'Decimal' is not valid. "

    Function PartsTotal() As Decimal
        ' Function for the Parts total without tax.
        Dim decPartsTotal As Decimal


        If chkMuffler.Checked = True Then
            If CBool(CDec(CDbl(txtPart.Text) >= 0)) Then

                decPartsTotal = (CDec(CDbl(txtPart.Text) * decMUFFLER))
            Else
                MessageBox.Show("Parts cannot be less than 0.")

            End If
        End If

        Return decPartsTotal

    End Function
    Function LaborFee() As Decimal
        ' function for the labor hourly charge.
        Dim decLABOR_FEE As Decimal

        If CBool(CDec(CDbl(txtLabor.Text) >= 0)) Then
            decLABOR_FEE = (CDec(CDbl(txtLabor.Text) * decLABOR_CHARGE))
        Else
            MessageBox.Show("Please enter a valid number for labor fee.")
        End If

        Return decLABOR_FEE

    End Function

I don't know how but this worked.

and wait, that was a no go.

OKAY! Now I am getting conversion errors for both functions Labor and Parts.

Labor:

 Function LaborFee() As Decimal
        ' function for the labor hourly charge.
        Dim decLABOR_FEE As Decimal

        If CDbl(txtLabor.Text) >= 0 Then
            decLABOR_FEE = (CDec(txtLabor.Text) * decLABOR_CHARGE) ' conversion error. option strict on.
        Else
            MessageBox.Show("Please enter a valid number for labor fee.")
        End If

        Return decLABOR_FEE

    End Function

Parts:

 Function PartsTotal() As Decimal
        ' Function for the Parts total without tax.
        Dim decPartsTotal As Decimal


        If chkMuffler.Checked = True Then
            If dblPart >= 0 Then

                decPartsTotal = (CDec(txtPart.Text) * decMUFFLER) ' conversion error. option strict has to be on!
            Else
                MessageBox.Show("Parts cannot be less than 0.")

            End If
        End If

        Return decPartsTotal

    End Function

Option strict is a must for this assignment. I cannot figure out any other way to do this without crashing the whole project, any value input in the text boxes ( named txtLabor and txtPart ) simply cause a crash. even valid numbers. the same error for both " Cannot convert to decimal from string"