Hi Omar,
1. This should not be happening. Is this occurring only for this clause template or for any template.
2. You have to fill in the details for the clause and then use the 'Set Document' to upload the template for the clause..
Kindly let us know what version of SAP Sourcing and support pack you are testing this on..
If you are unable to resolve this , please create an OSS ticket and an we will provide you assistance..
Thanks
Prasad