SAP- Connect to SAP from using .net connectors - error calling SAP query

[user123567]

getting below error when calling below code:

‘destination FSD failed when calling RFC_METADATA_GET’

‘Exception thrown: 'SAP.Middleware.Connector.RfcCommunicationException' in sapnco.dll

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Private Shared Function Invoke(ByVal destination As RfcDestination, ByVal table As String, ByVal fields As List(Of SAPFieldItem), ByVal options As List(Of SAPFieldItem))

Try

'04052022

Dim func As IRfcFunction = destination.Repository.CreateFunction("RFC_GET_CUST") ' QUE_DOTNET__01 'RFC_GET_CUST

'set fields

If fields IsNot Nothing Then

Dim fs As IRfcTable = func.GetTable("FIELDS")

For i As Integer = 0 To fields.Count - 1

fs.Append()

fs.CurrentIndex = i

fs.SetValue("FIELDNAME", fields(i).FieldId)

Next

End If

'set options

If options IsNot Nothing Then

Dim opts As IRfcTable = func.GetTable("OPTIONS")

For i As Integer = 0 To options.Count - 1

opts.Append()

opts.CurrentIndex = i

opts.SetValue("TEXT", If(i > 0, " AND ", "") + options(i).makeWhere)

Next

End If

func.SetValue("QUERY_TABLE", SAPFieldItem.escape(table))

func.Invoke(destination)

Dim result As New List(Of Dictionary(Of String, String))

Dim index As Integer = 0

Dim struct As IRfcTable = func.GetTable("FIELDS")

Dim columns As New Dictionary(Of String, Integer)

For i As Integer = 0 To struct.Count - 1

struct.CurrentIndex = i

columns.Add(struct.GetString("FIELDNAME"), struct.GetInt("LENGTH"))

Next

Dim data As IRfcTable = func.GetTable("DATA")

For i As Long = 0 To data.Count - 1

data.CurrentIndex = i

Dim line = data.GetString("WA")

Dim row As New Dictionary(Of String, String)

Dim position As Integer = 0

For Each c In columns

If position + c.Value <= line.Length Then

row.Add(c.Key, line.Substring(position, c.Value).Trim)

ElseIf position <= line.Length Then

row.Add(c.Key, line.Substring(position).Trim)

Else

row.Add(c.Key, String.Empty)

End If

position += c.Value

Next

result.Add(row)

Next

Return result

Catch ex As Exception

Console.WriteLine(ex.Message)

End Try

End Function"

[user123567]

i am using sapnco.dll and sapnco_utils.dll libraries V 3.0.2.0