Conflict between modal popup extender and hover menu extender

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ASP.NET

i have a modal popup extender in master page it work fine,
Then I add a hover menu extender in a data-list, at the same master page,
after that
popup extender Not work,
And if i remove hover menu extender than popup extender work Well,
what can i do Plz Suggest me?


And If I use modal popup extender at Master Page And hover menu extender in simple page which Access Master Page then They Both Work Well;