Alternate access mapping and IRM in SharePoint 2010

Dear All, 

We have an issue with RMS with SharePoint

Please find it below

The following scenario is happening when we open a document from IRM enabled Library


Iteration 1( While creating a web application if we provide public url as same as machine name (eg:sharepoint))

http://sharepoint:123456 is your central admin

http://sharepoint:654321 is your site collection

Its working fine



Iteration 2 ( While creating a web application if we provide public url as other than machine name (eg:mossservername))

http://sharepoint:123456 is your central admin

http://mossservername:654321 is your site collection


we are facing the following issue when we open a document from IRM enabled Library

When I tried to open Excel I got following error
Microsoft Office Excel cannot access the file 'http://mossservername:654321 /Documents/Filename.xlsx'. There are several possible reasons:
 
·         The file name or path does not exist.
·         The file is being used by another program.
·         The workbook you are trying to save has the same name as a currently open workbook.
 
When I tried to open Word , I got following error
Microsoft Office Word:
"http://mossservername:654321 /Documents/Filename.doc" does not exist.Check your spelling or try another path


If We done following things in Alternate Access Mappings its working fine 

Default URL : http://mossservername:654321
Extranet URL : http://sharepoint:654321

we need to make rms working on http://mossservername:654321 rather than extranet url
Please help us to sort it out

Thanks in Advance
Scorpion