Restoring A Sql Express Backup To Sql 2005

i'm trying to set up one of the asp.net website starter kits and part of the process is to backup the sql express db and then import it into the sql 2005 at the web hosting account.  it's not working and i'm wondering if there's any difference between the backups they make.  the sql express makes a file with a .bak extension and the sql 2005 at the host makes a file with a .sqlbak extension.  i was assuming that was just a naming thing and not a structural thing but the host's tech support has said:

"This sort of thing happens when the database being imported is not properly formatted. You can try downloading and using sql express from microsoft to see if you can do it manually, but most likely you will need to save your database again properly set for import to an mssql server rather than however you did."

all i had done was rename the .bak file from express to .sqlbak as that was the choice for backup files.

i will note that it also failed importing the .mdf, which works fine locally with the site but i did make some changes to it from the original that came with the starter kit.

should a backup file made with sql express (using sql management studio express, by right clicking on the file and choosing tasks > backup) normally be importable by sql 2005?

or, i suppose, does it make sense that a db that works fine locally with sql express (within a visual web developer express project anyway) would actually be "formatted" in a way that would cause it to fail to import into sql 2005?

thanks much for any assistance.