Project builds well but it can`t run

Question

My windows application compiles with no errors but fails to run and a gives a message that says "Proj.vshost.exe' (CLR v4.0.30319: POS.vshost.exe): Loaded 'C:\Users\Arnold\Documents\Visual Studio 2015\Projects\Proj\bin\Debug\MetroFramework.dll'. Cannot find or open the PDB file." .The MetroFramework.dll is referenced and it exists in the project.

Am wondering what the problem could be.