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Microsoft OLE DB Provider for ODBC Drivers error \'80040e07\'

[Microsoft][ODBC Microsoft Access Driver] Data type mismatch in criteria expression.

/script/asp/snyde/snydekoder.asp, line 67

her er linje 67:
Set rs = Conn.Execute (str_sql2)

og her er lidt af koden:
<%
Set Conn = Server.CreateObject(\"ADODB.Connection\")
Conn.Open \"DRIVER={Microsoft Access Driver (*.mdb)}; DBQ=\" & server.MapPath(\"database.mdb\")
str_sql2 = \"SELECT * FROM jwsnydekoder WHERE godkendt=\'Ja\'\"
If Request(\"alfa\") > \"\" Then str_sql2 = str_sql2 & \" AND instr(\'\" & LCase(Request(\"alfa\")) & \"\',lcase(left(navn,1)))>0\"
Set rs = Conn.Execute (str_sql2)
%>