Not able to debug after doing version updation in keil

Hi,

I have upgraded my keil IDE:: LPC1800_DFP version from 2.6.0 to 2.7.0. my program is built with no error. Now i am trying to debug my program using ULINK2. But i am not able to debug. it is always showing error message.
"could not stop cortex M device, please check the JTAG".

But the same setup is working fine and able to debug, when i am using version 2.6.0.

Even i tried with changing the JTAG clock as 1MHz and 10MHz

Could anyone tell how can i resolve this issue

Thanks

Alagappan M