Getting error when creating instances of static mesh

When I move the code to BeginPlay, I get these messages on the screen:

Failed to set ISMC Mesh
In Begin Play

When I hit stop, I get a dialog box with this error:

PIE: Error: Blueprint Runtime Error: "Accessed None trying to read property ISMC". Node:  Set Static Mesh Graph:  EventGraph Function:  Execute Ubergraph Create Meshes Blueprint:  CreateMeshes