getting " Object type cannot be converted to target type." with dataAdapter using storedProc

[Dica]

i'm getting an error when trying set my dataAdapter's selectCommand. the
sqlStatement is a storedProc which takes parameters, so it's constructed as:

sqlSelectComman d1.CommandText = "[uspProjectListU ser]";

sqlSelectComman d1.CommandType = System.Data.Com mandType.Stored Procedure;

sqlSelectComman d1.Connection = sqlConnection1;

sqlSelectComman d1.Parameters.A dd(new
System.Data.Sql Client.SqlParam eter("@RETURN_V ALUE",
System.Data.Sql DbType.Int, 4, System.Data.Par ameterDirection .ReturnValue,
false, ((System.Byte)( 0)), ((System.Byte)( 0)), "",
System.Data.Dat aRowVersion.Cur rent, null));

sqlSelectComman d1.Parameters.A dd("@iCompanyID ", SqlDbType.Int). Value = 1;

sqlSelectComman d1.Parameters.A dd("@iUserID", SqlDbType.Int). Value = 4;

when i pass this to my dataAdapter as:

oDataAdapter.Se lectCommand = sqlSelectComman d1;

i get an error:

" Object type cannot be converted to target type."

i've tried commenting out the parameters, and then have no problems setting
the dataAdapter's selectCommand.

how can i fix this?

tks