FOP 0.93 hyphenate Problem

Hi All,
       I am using FOP .93 version in my project. I've used hyphenate
attribute to fo:block in XSL. I've also included fop-hyph.jar file in lib
folder. According to my observation, some words are getting hyphenated and
some are not. I am not able to track why this problem is coming. Can anybody
help me please?
I am attaching some piece of code where i've applied hyphenate attribute.



<fo:table-cell border-width="0.5pt" border-style="solid" padding-left="1mm"
padding-right="1mm" padding-top="0.5mm" padding-bottom="0.5mm"
text-align="center" wrap-option="wrap" >

<fo:block hyphenation-keep="auto" hyphenate="true" language="en">

 <xsl:apply-templates/>

 </fo:block>



<xsl:template match="p">

<fo:block>

<xsl:apply-templates/>

</fo:block>

</xsl:template>