Hi Chaaya Chares,
Currently in OpenERP v7, in  Products Label report, blank name shows product's Variants name('Variants' Field), 
for example, Open any Product, Just type any string in Product's Variants field, and print Products Label Report, you can see your string instad of blank name
if you want to show product name, you must do changes in 'product/report/product_label.xsl'. in this file just replace
<para style="nospace"><xsl:value-of select="variant"/></para>
with 
<para style="nospace"><xsl:value-of select="product"/></para>
Now  restart your openerp server and  update product module, after updating module  you can see product's name instead of blank name in  Products Labels Report.
hope it works for you.
Check the print out settings in your report editor. It might give you a clue to what is happening