Actions not working in LEAD

hi all

i have a problem that actions assigned in LEAD transaction isnt working.i have checked all the customising that in action profile workflow is attached and action is assigned to the transaction but when i open the transaction in menu "maintain lead" under the action tab ,am not able to select the action as it is freezed or greyed.

i have tried using standard transaction under which standard actions are assigned but of no use,strangely actions are working in activity and marketing planner.

please suggest how should i solve this.

help will definitely be appreciated.

best ragards

ashish