クラスを読みに行かない

Question

Private Sub PurchaseForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim dt As DataTable = _SQLpublish.PurchaseInfomation(mastercostomerCd)
DataGridView1.DataSource = dt
End Sub

Public Function PurchaseInfomation(ByVal costomerCd) As DataTable
Dim db As New DBManager(DB_STRING)
Dim sb As New StringBuilder

	sb.Append("SELECT")
	sb.Append("  NS_KOKYAKU.COSTOMER_NM")
	sb.Append("  , NS_ITEMS.ITEM_NM")
	sb.Append("  , NS_MAKER.MAKER_NM")
	sb.Append("  , NS_KONYUJOHO.PURCHASE_DATE")
	sb.Append("  , NS_SHAIN.SHAIN_NM ")
	sb.Append("FROM")
	sb.Append("  (((NS_KOKYAKU ")
	sb.Append("          LEFT OUTER JOIN NS_KONYUJOHO  ON NS_KOKYAKU.COSTOMER_CD = NS_KONYUJOHO.COSTOMER_CD)")
	sb.Append("        LEFT OUTER JOIN NS_ITEMS ON NS_KONYUJOHO.ITEM_CD = NS_ITEMS.ITEM_CD)")
	sb.Append("      LEFT OUTER JOIN NS_SHAIN  ON NS_KONYUJOHO.SHAIN_CD = NS_SHAIN.SHAIN_CD) ")
	sb.Append("  LEFT OUTER JOIN NS_MAKER   ON NS_KONYUJOHO.MAKER_CD = NS_MAKER.MAKER_CD")
	sb.Append(" WHERE")
	sb.Append("NS_KONYUJOHO.COSTOMER_CD =").Append(costomerCd)



	Return db.SelectSql(sb.ToString).Tables(0)
End Function

_SQLpublish.PurchaseInfomation(mastercostomerCd) のところでNULLが発生しましたとなるのですがmastercostomerCdはしっかりとれているのです。
_SQLpublishのクラスに読みに行ってないような感じなのですがなぜなのでしょうか？

Answer 1

インスタンス化が失敗してたのでできませんでした
お手数おかけしました