Request for permission of type 'Microsoft.Office.Access.Server.Security.AccessServicesPermission,

Below are steps to solve above problem

(1) Modify the C:\Program Files\Microsoft SQL Server\MSRS10_50.MSSQLSERVER\Reporting Services\ReportServer\rsreportserver.config file on the Reporting Services server. Under the node, under the node, add the ADS data extension. For example:
<Extension Name="ADS" Type="Microsoft.Office.Access.Reports.DataProcessing.AdsConnection, Microsoft.Office.Access.Server.DataServer, Version=14.0.0.0, Culture=Neutral, PublicKeyToken=71e9bce111e9429c"/> -->


(2)Modify the rssrvpolicy file on RS server.

Add the following XML code in the file under the node.

<PermissionSet class="NamedPermissionSet" version="1" Name="ReportExpressionsDefaultPermissionSet">
<IPermission class="SecurityPermission" version="1" Flags="Execution" />
<IPermission class="Microsoft.Office.Access.Server.Security.AccessServicesPermission, Microsoft.Office.Access.Server.Security,
Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" version="1.0" Flags="CalculationCallback" />
</PermissionSet>


(3) In the node, find the following line and change PermissionSetName from “Execution” to “ReportExpressionsDefaultPermissionSet”

<CodeGroup class="UnionCodeGroup" version="1" PermissionSetName="Execution" Name="Report_Expressions_Default_Permissions"
Description="This code group grants default permissions for code in report expressions and Code element. ">