i am trying to update a ObjectPermissions Object in slaesforce such that a profile will get the permissions to access a object similar to other profile.

i write a code

my code segment is 

PermissionSet set1 = [SELECT Id From PermissionSet Where profileId= :SourceProfileId LIMIT 1] ;
PermissionSet set2 = [SELECT Id FROM PermissionSet Where profileId= :TargetProfileId LIMIT 1];
List<ObjectPermissions> oo = [SELECT Id,SObjectType,ParentId,PermissionsCreate,PermissionsDelete,PermissionsEdit,PermissionsModifyAllRecords,PermissionsRead,PermissionsViewAllRecords FROM ObjectPermissions WHERE ParentId = :set1.id];


List<ObjectPermissions> oo1 = [SELECT ParentId,Id,SObjectType,PermissionsCreate,PermissionsDelete,PermissionsEdit,PermissionsModifyAllRecords,PermissionsRead,PermissionsViewAllRecords FROM ObjectPermissions WHERE ParentId = :set2.Id] ;
Map<String , ObjectPermissions> source_obj = new Map<String,ObjectPermissions>();
Map<String , ObjectPermissions> target_obj = new Map<String,ObjectPermissions>();
for(ObjectPermissions o : oo)
{
source_obj.put(o.SObjectType,o);
}
for(ObjectPermissions o : oo1)
{
target_obj.put(o.SObjectType,o);
}
ObjectPermissions target,source;
for(String s : source_obj.keySet() )
{ if(target_obj.containsKey(s))
{ target = target_obj.get(s);
source = source_obj.get(s);
System.debug('Source is:'+source);
System.debug('Target is : '+target);
target.PermissionsCreate = source.PermissionsCreate;
target.PermissionsDelete = source.PermissionsDelete;
target.PermissionsEdit = source.PermissionsEdit;
target.PermissionsModifyAllRecords = source.PermissionsModifyAllRecords;
target.PermissionsRead = source.PermissionsRead;
target.PermissionsViewAllRecords =source.PermissionsViewAllRecords;
update target;
}
else {target = new ObjectPermissions(SObjectType = s );
source = source_obj.get(s);
target.PermissionsCreate = source.PermissionsCreate;
target.PermissionsDelete = source.PermissionsDelete;
target.PermissionsEdit = source.PermissionsEdit;
target.PermissionsModifyAllRecords = source.PermissionsModifyAllRecords;
target.PermissionsRead = source.PermissionsRead;
target.PermissionsViewAllRecords =source.PermissionsViewAllRecords;
insert target; }
}

when the control come to this line 

update target;

it is giving error 

Update failed. First exception on row 0 with id 110i0000007KNEvAAO; first error: INVALID_CROSS_REFERENCE_KEY, You can't create, edit, or delete records for this permission set parent because it's associated with a profile. Parent ID: 0PSi00000009BE9: []

i am unable to figure it out why i am facing this error please some one help to resolve this error