I try to put checkbox-unchecked.png image file into the report of purchase_requisition here is my code:

<pageGraphics>
  <image file="img/checkbox-unchecked.png" x="10cm" y="10cm"/>
</pageGraphics>

The folder of the image file is located in the path addons/purchase_requisition/report/img/checkbox-unchecked.png And i'm using windows 7.

The error shows:

cannot identify image file
fileName=<open file u'C:\\Program Files (x86)\\OpenERP 7.0-20140221-003045\\Server\\server\\openerp\\addons\\purchase_requisition\\report\\img\\checkbox-unchecked.png', mode 'r' at 0x042D6D30> identity=[ImageReader@0x675fe90 filename=u'C:\\Program Files (x86)\\OpenERP 7.0-20140221-003045\\Server\\server\\openerp\\addons\\purchase_requisition\\report\\img\\checkbox-unchecked.png']
handle_pageBegin args=()

(<type 'exceptions.IOError'>, IOError("cannot identify image file\nfileName=<open file u'C:\\\\Program Files (x86)\\\\OpenERP 7.0-20140221-003045\\\\Server\\\\server\\\\openerp\\\\addons\\\\purchase_requisition\\\\report\\\\img\\\\checkbox-unchecked.png', mode 'r' at 0x042D6D30> identity=[ImageReader@0x675fe90 filename=u'C:\\\\Program Files (x86)\\\\OpenERP 7.0-20140221-003045\\\\Server\\\\server\\\\openerp\\\\addons\\\\purchase_requisition\\\\report\\\\img\\\\checkbox-unchecked.png']\n handle_pageBegin args=()",), <traceback object at 0x06DE7C38>)

Anyone has anyidea? Thank you very much