Struggling to call a custom function from with a custom function?

Struggling to call a custom function from with a custom function?

I have a few custom functions.  Some I need to use repeatedly so separated them with a view to calling them from within other functions.

However I cannot find the correct syntax to call the functions?  When I try to use the script builder (using Chrome Browser) the details do not get entered at all? - just blank? so I have no guidance on the syntax.  So I am trying to just add the syntax in in Free Flow Scripting>

Can someone please tell me how I reference a function from within my own CRM?

for example

UpdateStatusinRecord=thisapp.workflowspace.UpdateStatusinVendorRecord("Validated",VendorID.toLong());

Am I referencing the Function correctly if its caled "UpdateStatusinVendorRecord" ?  the function is in my workflow space?

The function I am using works prefectly well when run.

I continually get the error that the function does not exist?

Any help appreciated.