How to solve inconsistent accessibility: field type 'crystaldecisions.web.crystalreportviewer' is less accessible than field 'purchaseorderapplication.productreport1.crystalreportviewer1 page

When you drive a class, you can't do this:

protected class A
    {
    protected int I;
    }
public class B
    {
    public A a = new A();
    }

Because you are effectively "upgrading" the entire protected class to become public - since the entire A class is now available via the B class instance, the code that uses B also need to be able to access the full class A definition, and the protected status of A means that isn't possible outside the class and it's derived instances.

Probably, your CrystalReportViewer1 is declared as public or similar.