The vendor name is not case sensitive so while using the model, we should check the folder name created for the service file in Netsuite.
for example:
We have created the extension with the vendor name as JJ (capital letter)
and there may be the chance for creating the vendor name as jj(small letters)
The reason behind this, there is already created a vendor name as jj so if we created another extension with JJ it will use the same vendor for extension creation.