Overview:

When trying to submit a call Online that has Samples recorded, the Submit button is not responding after clicking on it. 

Root Cause:

The call has a Promotional Item and the Company Product checkbox is unselected for the Product. 

Solution: 

The Company Product checkbox must be selected on both the parent product record and the child product record in order to be available for Call Sampling.

Note: This issue is not happening Offline, because the Company Product checkbox is not validated when Submitting a Call Offline.

Related Documentation:

CRM Help Documentation: Configuring Products for Call Sampling