Import And Export SQL 2005 Maintenance Plan

I had created a maintenance plan and configure and scheduled my maintenace plan to run. I would like to save this package as a file into a source control. SO I use SSIS to export the package under stored packages->MSDB->Maintenace Plan. After that, I wanted to test my import process. So I deleted the packages under SSIS ->stored packages->MSDB->Maintenance plan and I use the import to add the package from my previously exported package stored in a file .dtxs extention.

So the problem is, after I imported my package. I lost the configured schedule and the job runs without doing anything. When I try to go in and make changes to the package, by adding a new schedule under SQL server -> management->maintenance plan. I receive a odd error message and it doesn't allow me to save the package.. The error message I got is...."GUID should contain 32 digits with 4 dashes (xxxxx-xxx-xx...)"

So my questions are: 1. why did the re-import loses the originally configure job run schedule. 2. why doesn't the re-import package works by backing up database as it was first setup. 3. why I cannot re-edit this package and saving the package error out?

Thank you for reading and for your helps! --Jon