vSphere Deploy error: Could not find any recognizable digits.

I Have a OVA package the deploys fine in vSphere 4.1, but when tried with vSphere 4.0 gives the following error message:

Error: The OVF package is invalid and cannot be deployed.

Could not find any recognizable digits.

The Deploy was done via vSphere client 4.0 (File --> Deploy OVF Template...)

Any help would be appreciated.

Thanks.