Timeout expired

Public Function Consultar(ByVal pParametro As String) As Data.DataSet
Dim conexaoMySQL As MySqlConnection
Dim Da As MySqlDataAdapter
Dim Ds As Data.DataSet
Dim SQL As New System.Text.StringBuilder
Dim Conexao As String
Conexao = ConfigurationManager.AppSettings("cStrConexao")
conexaoMySQL = New MySqlConnection(Conexao)
SQL.Append(" SELECT Pais_Codigo, Pais_Nome ")
SQL.Append(" FROM tb_paises ")
If Trim(pParametro) <> "" Then SQL.Append(" WHERE " & pParametro & "")
SQL.Append(" ORDER BY Pais_Nome ")
Da = New MySqlDataAdapter(SQL.ToString, conexaoMySQL)
conexaoMySQL.Open()
Ds = New Data.DataSet
Da.Fill(Ds)
Return Ds

End Function

error connecting: Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.