iOS Question iCallSubUtils library problem

I'm using B4i 4.01, a local Mac, and the iCallSubUtils (version: 1.00) library and the following code:

Public csu As CallSubUtils
csu.Initialize
csu.CallSubPlus(Me, "Chk_if_complete", 2000)

The build consistently fails with: fatal error: 'iCallSubUtils.h' file not found #import "iCallSubUtils.h"

Any clue as to what the problem is? This works in B4A.