The Value expression for the query parameter ‘XXXX’ contains an error: Index was outside the bounds of the array

Hi,

I have a report which runs fine in Visual Studio and i deployed it on to our Dev environment Report portal where it runs fine but , if i push the same report onto our Prod report server, I receive this error

<form action="Report.aspx?ItemPath=%2fStores%2fField%2fSales_By_Hour_Test" enctype="multipart/form-data" id="ui_form" method="post" name="ui_form">

An error has occurred during report processing. (rsProcessingAborted) The Value expression for the query parameter ‘Region’ contains an error: Index was outside the bounds of the array. (rsRuntimeErrorInExpression)

</form>

I am unable to figure out what it exactly means because the report runs fine on visual studio and also dev portal . Can some one please help me with this?

Thanks