How to convert one dataset to other dataset

dim ds as new MyDataset//This dataset i created while Using ADO.NET Connection
dim dset as new DataSet//This is Standard dataset
ds=SQLHelper.ExecuteDataSet(CommandType.StoredProcedure,"spr_Procedure1")

//There is no error in stored procedure
//Then i tried giving like this

dset=SQLHelper.ExecuteDataSet(CommandType.StoredProcedure,"spr_Procedure1")
ds=CType(dset,MyDataset)

//It shows the following error
System.InvalidCastException: Specified cast is not valid.

Or is there any way i can get the dataset using ADO.NET connection & stored
Procedure,If so plz send me the procedure,very urgent
Thanx in advance