Compute shader : Sending vertexposition to computeshader

I work on a compute shader particles system
i would love to initate particles from a vertex mesh position
i initate buffer like that

Code (csharp):

1.  
2.  
3.         _targetMeshBuffer.SetData(_targetMesh.vertices);
4.          
5.                 _compute.SetBuffer(kernel, "TargetMeshBuffer", _targetMeshBuffer);
6.      
7.  

and use it like that in the compute shader

Code (csharp):

1.  
2.     float3 test = TargetMeshBuffer[id].xyz;
3.  

And nothing append
any idea?

 

i juste forgot to invoke kernel before
var kernel = _compute.FindKernel("Update");