Hi Sadik,
Is your GDB session running, IIRC error messages like that that error message will come from GDB - so to diagnose why it is happening I would turn on MI trace in Preferences -> C/C++ -> Debug -> GDB -> Show the GDB traces consoles, and then examine the MI trace to identify what is different.
If not from GDB session, then I am not sure what is wrong. But eventually you want to end up at org.eclipse.cdt.debug.core.CDIDebugModel.createLineBreakpoint(String, IResource, int, int, boolean, int, String, boolean) (or similar method) to actually create a breakpoint.
You probably want to enable breakpoint target factories like the CEditor does, here is an example of enabling breakpoints for the disassembly (from org.eclipse.cdt.dsf.ui/plugin.xml):
<extension point="org.eclipse.debug.ui.toggleBreakpointsTargetFactories">
<toggleTargetFactory
id="org.eclipse.cdt.dsf.ui.ToggleBreakpointsTargetFactory"
class="org.eclipse.cdt.dsf.debug.internal.ui.ToggleBreakpointsTargetFactory">
<enablement>
<!-- Enable the breakpoint toggle for DSF Disassembly -->
<test
property="org.eclipse.cdt.dsf.debug.ui.isDisassemblyViewSupportsCBreakpoint">
</test>
</enablement>
</toggleTargetFactory>
</extension>
HTH,
Jonah