If you used the display-bitmap command, you must register this command in the [CONFIG] section of the project file exactly as follows:
[CONFIG]
RegisterRoutine("mvbmp","HDisplayBmp","USSS") ; display bitmap
RegisterRoutine("mvaudio", "HAudioCommand", "USSS")
RegisterRoutine("mvaff", "HAnimateCommand", "USSSS")
RegisterRoutine("ftui", "InitRoutines", "SU")
InitRoutines(qchPath, 1)
RegisterRoutine("ftui","ExecFullTextSearch","USSS")
CreateButton("ftSearch","&Search",
"ExecFullTextSearch(hwndApp,qchPath,`',`')")
BrowseButtons()