The form has no gadget created with name SYSTEM. Gadget could be text, list, option, frame etc. Please check your form and look for gadget system. Gadgets are usually declared on form setup.
$ in PML is a special character. Whenever PDMS detects $, all characters that follow it are treated as special command. Looking at your syntax the next character is, underscore '_' , in PML1 syntax, underscore is use when calling a gadget or method of any form. Example, q var !!MyFORM_textgadget is basically the same as using the PML2 style of calling q var !
!MyFORM.textgadget. So that is the reason whey PDMS has treated your code as calling a gadget and returned an error.
To avoid the same error in the future, do not create any variable with an underscore as the PDMS system will read it as you are calling a method or gadget of a form. Also if you reallt want to use $, do it this way $$.
