Can not add a tag to tags list

[andrei-galkin]

I have faced a weird case when I can not add a tag to the list because it fails at this part of code.

if (this._trigger('beforeTagAdded', null, {
                tag: tag,
                tagLabel: this.tagLabel(tag),
                duringInitialization: duringInitialization
            }) === false) {
                return;
            }

 if (this.options.singleField) {
                var tags = this.assignedTags();
                tags.push(value);
                this._updateSingleTagsField(tags);
            }

When I try to select the tag "Tech Value Distribution" it can not go trough the first condition and the tag is not added but other tags are fine and they come to the second condition and are added to the list. I am stuck and can not debug further through minified jquiry and do not have ideas how to find the reason why the statement

this._trigger('beforeTagAdded', null, {
                tag: tag,
                tagLabel: this.tagLabel(tag),
                duringInitialization: duringInitialization
            })  

executes and return false but for other tags it is always true.
Can some one share idea why the tag can not be added?

Thank you

PS
The version of the script is @Version v2.0 (06/2011)

[andrei-galkin]

Found the issue. Need to be attentive with data.