How to solve gtkdialog:9804 error

Hi while running my script I got this error

** (gtkdialog:9804): ERROR **: gtkdialog: Error in line 8, near token '>': syntax error

this is my script:

#!/bin/bash

cp -f im-logo.jpg im-changed.png
cp -f im-logo.jpg im-revert.png
echo -n 50 > /tmp/SB1

export MY_GUI='
<window title="bla" resizable="false">
<vbox width-request="400" border-width="10">
<hbox homogenous="true">
<colorbutton visible="false"
title="choose a color"
use-alpha="false" alpha="32896"
<variable>CB_1</variable>
<default>#025986</default>
<action>mogrify -fuzz `cat /tmp/SB1` "%" -fill $CB_1 -opaque "#0000ff" im-changed.png</action>
</colorbutton>
<pixmap auto-refresh="true">
<width>"237"</width>
<height>"237"</height>
<input file>im-changed.png</input>
</pixmap>
</hbox>
<hseparator></hseparator>
<hbox homogenous="true">
<button>
<input file>palette.png</input>
<action signal="button-press-event">activate:CB_1</action>
</button>
<spinbutton range-min="0" range-max="100" range-step="1">
<default>"50"</default>
<variable>SB_1</variable>
<output file>/tmp/SB1</output>
<action signal="leave-notify-event">save:SB_1</action>
</spinbutton>

<button image-position="2">
<width>80</width>
<height>75</width>
<input file>revert.png</input>
<action function="command">
cp -f im-test.png im-changed.png
</action>
</button>
</hbox>
<hbox homogenous="true">
<text>
<label>choose a color</label>
</text>
<text>
<label>set fuzziness</label>
</text>
<text>
<label>undo changes</label>
</text>
</hbox>
<hseparator></hseparator>
<hbox homogenous="true">
<button ok></button>
</hbox>
</vbox>
</window>
'
gtkdialog -p MY_GUI

Please help me solving this error. This is my first gtkdialog script. I dont know what to do exactlly. Could not find anything in Google. Thanks!!!