Is the sentence was not correct gramatically?

The sentence "was not correct grammatically" is grammatically incorrect. It should be:

"The sentence was not grammatically correct."

Here's why:

* Subject-verb agreement: "Sentence" is singular, so the verb should be "was," not "were."

* Adjective order: "Grammatically correct" is the proper order for these two adjectives.

Let me know if you have any other sentences you'd like to check!