Pegando variavel e jogando no Sql

Po galera ta osso:

Alguem me ajuda aae??? pq esse SQL nao recebe corretamente a variavel setada conforme exemplo??

ta ossoooo??

<%
Dim Busca
Dim Busca_cmd
Dim Busca_numRows
Dim a,b,c
a = "010101010101010"
b = "PR01010-1"
c = "0158795"

Set Busca_cmd = Server.CreateObject ("ADODB.Command")
Busca_cmd.ActiveConnection = MM_dcdcdev_STRING
Busca_cmd.CommandText = "SELECT distinct B.texto as Texto_Rel, B.DT as Data_Referencia,A.num_cgc as cnpj,A.cod_forn as Fornecedor FROM historico_web A,v_p B WHERE A.relac = B.relac AND A.nr_doc = B.nr_doc and A.ano_documento = B.ano_documento and A.cod_forn = B.COD_FORN and A.num_cgc = '"&a&"' and B.COD = '"&b&"' AND A.cod_forn = '"&c&"' AND to_char(B.DT, 'mm') = '05' AND to_char(B.DT, 'YY') = '13' AND B.Cod_Tipo_carteira = '2' and B.Flag_Estorno = '0' ORDER BY B.DT"
Busca_cmd.Prepared = true

Set Busca = Busca_cmd.Execute
Busca_numRows = 0
%>