error when inserting into a internal table

hello.

I get the fowolling error.

An exception occurred that is explained in detail below.

The exception, which is assigned to class 'CX_SY_OPEN_SQL_DB', was not caught

and

therefore caused a runtime error.

The reason for the exception is:

In a SELECT access, the read file could not be placed in the target

field provided.

Either the conversion is not supported for the type of the target field,

the target field is too small to include the value, or the data does not

have the format required for the target field.

I did a join of 5 table and it is inseting into an interal table wich tpye is al the fields that i am pulling from the other tables. can someone please help. thanks