I cant run Llama() function on GPU

I am using Llama() function for chatbot in terminal but when i set n_gpu_layers=-1 or any other number it doesn't engage in computation. In comparison when i set it on Lm Studio it works perfectly and fast I want the same thing but in terminal.
Any one knows what could be the problem?

model = Llama(model_path= "zephyr-7b-beta.Q4_K_M.gguf", n_gpu_layers=-1, n_ctx=2048,verbose=False)