You receive a "use of unconstructed message" error when building your project

Problem

When you compile your BizTalk project, you receive the error "use of unconstructed message ''".

Cause

This error occurs when an unconstructed message is used in a Send shape.

Resolution

To resolve this issue, add a Construct Message shape to the orchestration. Include the Construct Message shape before the Send shape that is bound to the Web service.

Source: Microsoft