Here i wrote a proposal vfpage on opportunity i am trying to convert as pdf,here i am getting this error:PDF
generation failed.Check the page markup is valid.
 Can anyone please suggest on the same...

<apex:page standardController="LM_Opportunity__c" renderAs="pdf" sidebar="true" extensions="proposalclass" >
 <apex:form >
<style> 
     tr.spaceUnder > td
     {
     padding-bottom: 2em;
     }
     tr.spaceUnder1 > td
     {
     padding-bottom: 1em;
     }
</style>
    <table align="center" cellspacing="0" cellpadding="0" border="1" width="100%"> 
         <tr>
         <tr width="1%"></tr>
              <table  width="100%" align="right">
                   <tr >
                         <td align="right"><b>Proposal No :  <apex:outputText value="{!L.Proposal_Number__c}"> </apex:outputText></b></td>            
                   </tr>
                   <tr>  
                        <td align="right"><b>Proposal Date : <apex:outputText value="{!Now()}"> </apex:outputText></b></td>            
                   </tr>                                                   
                   </table> 
                              
                   <table >
                           <tr class="spaceUnder1">
                                 <td><b>To,</b></td>
                           </tr>
                           <tr>
                                 <td><b><apex:outputtext value="JAISIM-FOUNTAINHEAD"/></b></td>
                           </tr>
                           <tr>
                                 <td><b>#175/1,PAVILLION ROAD,</b></td>
                           </tr>
                           <tr>
                                 <td><b>JAYANAGAR EAST,1ST BLOCK,</b></td>
                           </tr>
                           <tr class="spaceUnder">
                                 <td ><b>BANGALORE-560011</b></td>
                           </tr>
                           <tr class="spaceUnder1">
                                 <td><b>Kind Attn :</b>&nbsp;{!L.Kind_Attn__r.Name}</td>
                           </tr>
                            <tr class="spaceUnder1">
                                 <td>Dear Madam,</td>
                           </tr>
                            <tr class="spaceUnder1">
                                 <td>Project:</td>
                           </tr>
                           <tr class="spaceUnder1">
                                 <td><b>Sub: Proposal For{!L.Name}</b></td>
                           </tr>
                           <tr>
                                 <td>This has reference to the discussions you had with our Director during his visit to your office.</td>
                           </tr>
                           <tr>
                                 <td>We Provide your organization with a purchasing channel based on ease,trust,and dependability.Our</td>
                           </tr>
                           <tr>
                                 <td>established relationships, our design and planning center in Bangalore and network of reliable global</td>
                           </tr>
                           <tr>
                                 <td>manufacturers,eliminates the intermediaries,taking out the guess work and advancing your supply</td>
                           </tr>
                           <tr>
                                 <td>chain, without sacrificing efficiency or product quality.By utilizing our "Complete Service Chain",</td>
                           </tr>
                         
                           <tr>
                                 <td>Liquid Metal will meet your Furniture needs.We are your global design team,sourcing agent,quality</td>
                           </tr>
                           <tr class="spaceUnder1">
                                 <td>control,and freight-forwarder-all in one.</td>
                           </tr>
                           <tr class="spaceUnder1">
                                 <td>Enclosed is our proposal for your requirement of Alchemy system for maintec Project.</td>
                           </tr>
                           <tr class="spaceUnder">
                                 <td>We look forward to an opportunity to work with you in this project.</td>
                           </tr>
                           <tr class="spaceUnder1">
                                 <td>Thanking you</td>
                           </tr> 
                           <tr class="spaceUnder">
                                 <td><b>For Liquid Metal Furniture Private Limited</b></td>
                           </tr>
                           <tr>
                                 <td><b>{!L.Opportunity_Owner__r.Name}</b></td>
                           </tr> 
                           <tr>
                                 <td><b>Manager-Business Developement</b></td>
                           </tr>    
                  </table>                                                  
                           </tr>
                  </table>
    
    </apex:form>
</apex:page>