Happy sighs!!!
Ha ha ha, I forgot to add the windows authentication attribute
Trusted_Connection=Yes;
or
Integrated Security=SSPI;
to my connection string, sometimes I let the stress to win :(
Now i got rid of the error be adding the Trusted_Connection attribute to my connection string and removed credentials details.
<add name="Entities" connectionString="metadata=res://*/Model.csdl|res://*/Model.ssdl|res://*/Model.msl;provider=System.Data.SqlClient;provider connection string="Data Source=MA000XSXXXXX\Sample;Initial Catalog=Test; Trusted_Connection=Yes; MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient"/>
Now it works good.