Gridview filtered expression date

I am trying to search by a date in a gridview using asp in vb2010. My webpage displays, but when I try to seach using my date criteria it generates an error message.  Attached is the code I have entered. Please let me know if you see where I am doing something wrong. I am given the following error noted (in the attached code) when attempting to search any field. All search function works as advertised.  I just need to figure out how to add a
search function to return the [DateDue] parameter.

Any help they can give me would be greatly appreciated

ShaePNC
code1.docx