I developed  simple soap api from one of my org and consumed it in another one ....

When i am calling it from another org ....it gives me the below error

First error: Web service callout failed: WebService returned a SOAP Fault: INVALID_SESSION_ID: Invalid Session ID found in SessionHeader: Illegal Session faultcode=sf:INVALID_SESSION_ID faultactor=

public class LogInfo {
public String category;
public String level;
private String[] category_type_info = new String[]{'category','http://soap.sforce.com/schemas/class/MyWebService','LogCategory','1','1','false'};
private String[] level_type_info = new String[]{'level','http://soap.sforce.com/schemas/class/MyWebService','LogCategoryLevel','1','1','false'};
private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/schemas/class/MyWebService','true','false'};
private String[] field_order_type_info = new String[]{'category','level'};

public class LoginHistory {
public String ApiType;
public String ApiVersion;
public String Application;
public String Browser;
public String ClientVersion;
public DateTime LoginTime;
public String LoginType;
public String LoginUrl;
public String Platform;
public String SourceIp;
public String Status;
public String UserId;
private String[] ApiType_type_info = new String[]{'ApiType','http://www.w3.org/2001/XMLSchema','string','0','1','true'};
private String[] ApiVersion_type_info = new String[]{'ApiVersion','http://www.w3.org/2001/XMLSchema','string','0','1','true'};
private String[] Application_type_info = new String[]{'Application','http://www.w3.org/2001/XMLSchema','string','0','1','true'};
private String[] Browser_type_info = new String[]{'Browser','http://www.w3.org/2001/XMLSchema','string','0','1','true'};
private String[] ClientVersion_type_info = new String[]{'ClientVersion','http://www.w3.org/2001/XMLSchema','string','0','1','true'};
private String[] LoginTime_type_info = new String[]{'LoginTime','http://www.w3.org/2001/XMLSchema','dateTime','0','1','true'};
private String[] LoginType_type_info = new String[]{'LoginType','http://www.w3.org/2001/XMLSchema','string','0','1','true'};
private String[] LoginUrl_type_info = new String[]{'LoginUrl','http://www.w3.org/2001/XMLSchema','string','0','1','true'};
private String[] Platform_type_info = new String[]{'Platform','http://www.w3.org/2001/XMLSchema','string','0','1','true'};
private String[] SourceIp_type_info = new String[]{'SourceIp','http://www.w3.org/2001/XMLSchema','string','0','1','true'};
private String[] Status_type_info = new String[]{'Status','http://www.w3.org/2001/XMLSchema','string','0','1','true'};
private String[] UserId_type_info = new String[]{'UserId','http://soap.sforce.com/schemas/class/MyWebService','ID','0','1','true'};
private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/schemas/class/MyWebService','true','false'};
private String[] field_order_type_info = new String[]{'ApiType','ApiVersion','Application','Browser','ClientVersion','LoginTime','LoginType','LoginUrl','Platform','SourceIp','Status','UserId'};
}

public class LoginIp {
public DateTime ChallengeSentDate;
public DateTime CreatedDate;
public Boolean IsAuthenticated;
public String SourceIp;
public MYWebservice34.User_x Users;
public String UsersId;
private String[] ChallengeSentDate_type_info = new String[]{'ChallengeSentDate','http://www.w3.org/2001/XMLSchema','dateTime','0','1','true'};
private String[] CreatedDate_type_info = new String[]{'CreatedDate','http://www.w3.org/2001/XMLSchema','dateTime','0','1','true'};
private String[] IsAuthenticated_type_info = new String[]{'IsAuthenticated','http://www.w3.org/2001/XMLSchema','boolean','0','1','true'};
private String[] SourceIp_type_info = new String[]{'SourceIp','http://www.w3.org/2001/XMLSchema','string','0','1','true'};
private String[] Users_type_info = new String[]{'Users','http://soap.sforce.com/schemas/class/MyWebService','User','0','1','true'};
private String[] UsersId_type_info = new String[]{'UsersId','http://soap.sforce.com/schemas/class/MyWebService','ID','0','1','true'};
private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/schemas/class/MyWebService','true','false'};
private String[] field_order_type_info = new String[]{'ChallengeSentDate','CreatedDate','IsAuthenticated','SourceIp','Users','UsersId'};
}

how to rectify the error?????

THanks