Let's say we have some requirements
Req1: User name will accept 6-10 character alpha value.
Req2: On click of Submit button, application will show error message "Please enter value or character between 6 to 10 including" for invalid boundary value.
In this case if we are designing test cases for invalid boundary values of 5 and 11, those would be positive test cases, since we are also verifying the error message, which is mentioned in requirement.
What would be negative test case for this scenario?