Please help!!! This expression must have a constant value

Question

I try to work with cfc and cfinvoke and not sure why I got this error. Searched
in google for answer but still don't get any. Can anyone help please...not sure where
I had it wrong...I thought my codes should work (?)
When a form is submitted I have this codes in formaction.cfm, I captured all the form fields in a structure:
<CFSET st_Registration = {Salutation="#Trim(Form.Salutation)#", FName = "#Trim(Form.FName)#", MName = "#Trim(Form.Mname)#",LName =  "#Trim(Form.LName)#" .......etc }/>
Then I set all the required fields:
 <CFSET ReqFields ="Salutation,FName,LName,Addr1,City,State,Zip,Country,Phone,Email,username,password">
<!--- Then send the structure and req. fiels list to a function located in a component to verify required fields ---><cfset CreateUserInfo = createObject("component", "airbucks.cfcomp.VerifyInput").init()> 
<CFINVOKE component="#CreateUserInfo#" method="Verify_ReqFields" st_Registration = "#st_Registration#" RequiredFields ="#ReqFields#" returnvariable="VerifyResult">
<CFIF #VerifyResult# IS "">
<cfdump var="#st_Registration#">
<CFELSE>
  <CFIF #st_Registration["Country"]# IS "USA">
<CFINCLUDE template="registration_ret.cfm">
  <CFELSE>
<CFINCLUDE template="registration_other_ret.cfm">
  </CFIF>
</CFIF>
<!--- Below is part of the component with the function for checking required fields --->
<cfcomponent displayname="VerifyInputData" output="false"> <CFFUNCTION name="Init" access="public" returntype="any" output="false" hint="Returns an initialized component instance.">
 <!--- Return This reference. --->
 <cfreturn THIS />
 </CFFUNCTION>
 <!--- Verify required fields --->
 <CFFUNCTION name="Verify_ReqFields">
 <cfargument name="st_Registration" type="struct" required="true">
 <cfargument name="RequiredFields" type="string" required="true"> 
<!--- check if req. fields are blank --->
 <CFSET ErrorList = "">
 <cfloop collection="#arguments.st_Registration#" item="KEY">
 <CFIF #Trim(st_Registration[KEY])# IS "">
 <CFSWITCH expression="#Trim(KEY)#">
 <CFCASE value="#arguments.RequiredFields#">
 <CFSET ErrorList = ListAppend(ErrorList, "#KEY#")>
 </CFCASE>
 </CFSWITCH>
 </CFIF>  
</cfloop>
 <CFRETURN ErrorList >
 </CFFUNCTION>
　 </cfcomponent>
    Here is the error:  
The following information is meant for the website developer for debugging purposes.
Error Occurred While Processing Request
This expression must have a constant value.
The error occurred in C:\Inetpub\wwwroot\AirBucks\registrationaction.cfm: line 55
53 :                              
54 : <!--- Verify required field based on the required list set above --->
55 : <cfset CreateUserInfo = createObject("component", "airbucks.cfcomp.VerifyInput").init()>
56 : <CFINVOKE component="#CreateUserInfo#" method="Verify_ReqFields" st_Registration = "#st_Registration#" RequiredFields ="#ReqFields#" returnvariable="VerifyResult">
57 :      

Answer 1

Thank you and I'll change my codes.
When I did the following, I still get the same error.
Isn't it CreateUserInfo is the object?
<cfset CreateUserInfo = createObject("component", "airbucks.cfcomp.VerifyInput").init()>
<CFSET VerifyResult = CreateUserInfo.Verify_ReqFields(st_Registration, ReqFields)> 
Using cfinvoke used to work.
The following information is meant for the website developer for debugging purposes.
Error Occurred While Processing Request
This expression must have a constant value.
The error occurred in C:\Inetpub\wwwroot\AirBucks\registrationaction.cfm: line 54
52 : <!--- Verify required field based on the required list set above --->
53 :
54 : <cfset CreateUserInfo = createObject("component", "airbucks.cfcomp.VerifyInput").init()>
55 : <!---
56 : <CFINVOKE component="#CreateUserInfo#" method="Verify_ReqFields" st_Registration