this error field

Warning occurred while setting a field of an RoSGNode
-- Type mismatch occurred when setting the "category" field of a "ParseEpg" node
   at line 48 of file pkg:/components/ParseEpg/ParseEpg.brs

ParseEpg.brs

Function init()
  m.top.functionName = "go"
  m.top.control = "RUN"
End Function

Function go()

	readInternet = createObject("roUrlTransfer")
	m.content    = createObject("RoSGNode","ContentNode")
	
	readInternet.setUrl(m.top.uri)
	source=readInternet.GetToString()
	responseJSON = ParseJSON(source)
	
    dateNow = CreateObject("roDateTime")
    dateNow = dateNow.asSeconds() - 2000

	
	Category=[]
	numofcategories=responseJSON.Count()-1
	For c=0 To numofcategories
	   Cat={}
		Cat.Title=responseJSON[c].category
		Cat.Id=responseJSON[c].cve
		Category.Push(Cat)
		if responseJSON[c].items <> invalid
		For x=0 To responseJSON[c].items.Count()-1
			itemAA=responseJSON[c].items[x]
			'print itemAA.Title
            m.channel = m.content.createChild("ContentNode")
            m.channel.Title = itemAA.Title
            m.channel.streamFormat = itemAA.streamFormat
            m.channel.url = itemAA.StreamUrls
            'm.channel.HDSMALLICONURL = itemAA.HDPosterURL
			
			  For e=0 To responseJSON[c].items[x].epg_now.Count()-1
			    epgNowAA=responseJSON[c].items[x].epg_now[e]
				program = m.channel.createChild("ContentNode")
                 program.TITLE = epgNowAA.epg_after
                 program.PLAYSTART = dateNow + (e * 2000)
                 'program.PLAYDURATION = "2000"
			  Next
		Next
		end if
	Next
	
	m.top.content=m.content 'set top content field
	m.top.category=Category 'set top content field
	'print Category.Title
End Function

ParseEpg.xml

<?xml version="1.0" encoding="utf-8" ?>
<!--********** Copyright 2015 Roku Corp.  All Rights Reserved. **********-->

<component name="ParseEpg" extends="Task">
 <interface>
 <field id="uri" type="uri" />
 <field id="content" type="node" />
 <field id="category" type="assocarray" />
 </interface>
 <script type="text/brightscript" uri="pkg:/components/ParseEpg/ParseEpg.brs"/>
</component>