ACII.GetBytes in a switch statement C# Error- Unable to cast object type
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I have the following C# code-

switch (Convert.ToInt32(Encoding.ASCII.GetBytes(grdGrading.Text.Trim())))

grdGrading is a Data grid. 

I am currently getting this error - Unable to cast object of type 'System.Byte[]' to type 'System.IConvertible'.

Any ideas on what is causing that?

Thanks.