applescript file name error
===

I have a spreadsheet that our office uses for scheduling.  Each tab represents a month.  I am able to export each tab to a file named month1.csv, month2.csv... etc.  I have the following piece of code to open each months file and loop through it:

        repeat with b from 1 to 12
            	tell application "Finder"
        		set curFileName to (sourceFolder & "month" & b & ".csv") as string
        		--display dialog curFileName
        		set workingFile to read file (curFileName)
        		--display dialog "File has been read"
        		set AppleScript's text item delimiters to {ASCII character 13}
        		set theContents to text items of workingFile as list
        	end tell
    
    do stuff with the csv...
    
    end repeat
	

The script iterates through the first month and then when b = 2 I get this error:

    Finder got an error: File file Macintosh HD:Users:lorenjz:Documents:Manpower:,month,2,.csv wasn’t found.

What do I need to do to eliminate this error?