Error calling Child Package

Hi,

I have a Master package and a few child packages deployed on the same server. I have run the packages successfully many times. But today when i redeployed the Packages, I am getting error while calling one the child package.

Error: Error 0xC0012050 while preparing to load the package. Package failed validation from the ExecutePackage task. The package cannot run.

While the other child packages are being called successfully, its quite strange the the process if failing for one child package. The settings for all the child packages are same in the Master Package.

I am calling the Master Packge through SQL Agent Job.

Any sugggestions please

Regards Yuktah