Make sure if you are trying to change it that you change it in all the partial classes that might have got created. such as classname.designer.cs
I change mine all the time since it oftens adds a folder name and I don't always want that. Also, if you right click the project in the solution explorer and go to the properties of the project, you can set the default namespace name.
Tim

>>>When I generate my DS the default NameSpace is Project Name. I want to add Company's name first, so it should be
>>>
>>>CompanyName.ProjectName.DataSets
>>>
>>>However, it seems to not take it.
>>>
>>>Do you think it's OK to leave without Company Name or what should I do to insert it?
>>
>>I think it is always good to encapsulate your code into your corporate namespace. For example, in my framework, all classes are part of a specific namespace. So, by that, I avoid any conflict with another namespace that can have the same name.
>
>Right, but I just generated my Datasets using designer. In the Designer code I tried to insert my company name. prefix, but it seems like it didn't take it. So, may be there is some way to set it using the designer?
>
>Thanks again.