Can change the field type after creating the table in sql server 2008

I am having an minor problem using sql server 2008. When I go for create an database table, after that, i can't change the field type at all(showing an permission error). I tried to set an field as primary key after the table created. I think, i w开发者_StackOverflowill have to change some settings somewhere. But, don't know where. Please help.

Regards

If you just created the table I'm going to assume it's unlikely to be a permissions error. You probably need to turn this option off in Management Studio.