Sqlite in Adobe Air, Data type mismatch

Question

Hello, I've been using Adobe Air framework (with JavaScript) and a sqlite 3 database. Everything worked fined, but after a while the Db started throwing Data type mismatch: could not convert text value to numeric value errors. As best I can recall, I've done no modification to either the database schema or the JS code. The SQL command is the following:

UPDATE products_original SET purchase_id='7894', sold_qty=sold_qty+1 WHERE id='11786' 

Interestingly, when using an external program to connect to the sqlite database, the same command doesn't throw an error. Could you please help me with this issue?

EDIT: The columns are all INTEGER types.