what Im about to post in this an the following post is from the takhreej of akhoona Abu Zubayr since i beleive he di the best takhreej of it in the english language

1) To call upon other than Allah for a need, such as rain, etc, while believing that the one being addressed will answer the call is Shirk by agreement. For example: O Prophet! Send us rain!

2) To call upon other than Allah for a need, such as rain, etc, while believing that only Allah will answer the call is Shirk, by agreement. For example: O Prophet! Send us rain!

3) To call upon other than Allah, asking them to intercede for us with Allah is also Shirk. For example: O Prophet! Intercede for us with Allah!

4) To call upon the Prophet, asking him to make du’a for us is Shirk. For example: O Prophet! Ask Allah to grant us rain!

5) To call upon Allah alone, asking Him by His Prophet is a valid difference of opinion in Fiqh where none is censured. For example: O Allah! I ask you alone by Your noble Prophet!