SQL & PL/SQL

Dear all,

We have difficulties to call Oracle Stored procedure from other vendor development tools.

Any body can help us, We have to integrate our Oracle Application with Visual Basic application. But there is No Oracle SQL command that can call Stored Procedure. Stored procedure just can be call from PL/SQL, and we just can send SQL command from VB.
We just try to change procedure to function and select the function. But unfortunately there are insert statement in our coding, and we can't have dml statement inside query.

I'm just wondering why it's so difficult to integrate oracle database with other vendor development tools ?

Thanks in Advanced