Server Error in '/rest' Application - Runtime Error

[mr.T]

Hello.
I'm kepp getting the Runtime error message, for every request i'm
sending.
At the beginning i got some error code. (code 2).
But now only this following Runtime error message:
-----------------------------The beginning of the
message--------------------------------
Server Error in '/rest' Application.

Runtime Error

Description: An application error occurred on the server. The current
custom error settings for this application prevent the details of the
application error from being viewed remotely (for security reasons).
It could, however, be viewed by browsers running on the local server
machine.

Details: To enable the details of this specific error message to be
viewable on remote machines, please create a <customErrors> tag within
a "web.config" configuration file located in the root directory of the
current web application. This <customErrors> tag should then have its
"mode" attribute set to "Off".


<!-- Web.Config Configuration File -->

<configuration>
<system.web>
<customErrors mode="Off"/>
</system.web>
</configuration>

Notes: The current error page you are seeing can be replaced by a
custom error page by modifying the "defaultRedirect" attribute of the
application's <customErrors> configuration tag to point to a custom
error page URL.


<!-- Web.Config Configuration File -->

<configuration>
<system.web>
<customErrors mode="RemoteOnly"
defaultRedirect="mycustompage.htm"/>
</system.web>
</configuration>
-----------------------------The end of the
message--------------------------------

How can i check what i did wrong?