SSRS Tool Tip

Hi All

we have chart where SSAS Cube is the Source . we have created the tool tip . It is giving error in tool tip when LAC_ID is "ALL"  for other values the tooltip is working . How to handle "All" attribute hierarcy in tool tip .

Tool tip Expression using :

="LACId: " + Fields!LAC_Id.Value.ToString  + vblf +"Time: " + Fields!MyPeriod1.Value + vblf + "LU_SR Value: " +Sum(Fields!LU_SR.Value).ToString

Surendra Thota