I keep getting this error. Anyone knows what the heck it is?

Code:
Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately. 

Parser Error Message: File or assembly name AcmeVB, or one of its dependencies, was not found.

Source Error: 


Line 1:  <%@ Register TagPrefix="Acme" Namespace="AcmeVB" Assembly="AcmeVB" %>